A History of the Acadia's Island Explorer

From mid June to early October each year, the Island Explorer provides fare-free transit service between park destinations, local communities, and the Bar Harbor-Hancock County Regional Airport.

Regularly scheduled buses stop at specific destinations in the park-including campgrounds, carriage road entrances, and many trailheads. You can also flag down buses along their route; drivers will pick up passengers anywhere it is safe to stop.

The propane-powered Island Explorer buses-also equipped with bicycle racks-help reduce traffic congestion, parking, and air pollution problems on the island.

The Island Explorer was established in the late 1990s as a unique partnership between:

  • National Park Service
  • U.S. Department of Transportation
  • Maine Department of Transportation
  • Friends of Acadia
  • Six municipalities
  • Private businesses

Downeast Transportation, Inc., a nonprofit organization, operates the fleet of propane-powered buses. Park entrance fees help support the Island Explorer bus system.

One of the most visited national parks in the United States, Acadia National Park covers more than 46,000 acres of the eastern coast of Maine and provides visitors with opportunities to hike, bike, camp, horseback ride, boat, fish, and ski against a landscape of largely unspoiled forest and coastline. Established as a national park in 1929, Acadia National Park was created through private donations of land, money, and expertise, and today sits within a day’s travel of a few major East Coast cities and the Canadian provinces of New Brunswick and Nova Scotia. The majority of the acreage of Acadia National Park is located on Mount Desert Island (MDI), with additional facilities on the Schoodic Peninsula and the island of Isle au Haut.

Acadia National Park welcomes more than 4 million visitors per year, 90 percent of whom visit during the summer months. This level of visitation profoundly strains the park’s transportation infrastructure and adversely affects the region’s ecosystems. Emissions of air pollutants contribute to acid precipitation that damages the rocky soils characteristic of the Acadia National Park area; one park lake is chronically acidified. Emissions also contribute to the development of haze that impairs scenic views from Cadillac Mountain and elsewhere in the area

The impact of this level of visitation is also felt in the park’s gateway communities. Acadia National Park is unusual among national parks in its close connection to and association with the four townships that surround it. Unlike those national parks that have clearly defined boundaries, Acadia National park is closely intertwined with its surrounding towns, seamlessly sharing MDI. Visitors for whom Acadia National Park is the primary destination spend almost as much time in local towns as they do in the park since most of the overnight accommodations and support facilities are outside of the park.

One of the most noticeable and consequential impacts of heavy automobile traffic is congestion. The roads on MDI and in the park are few and narrow. They include the Park Loop Road, designed more for the scenic appreciation of the forests and coastline than for the efficient movement of thousands of vehicles each day. The towns themselves, particularly Bar Harbor, have narrow, crowded streets, lined with shops and filled with pedestrians and bicyclists. At peak traffic hours on MDI, in the late afternoon and early evening, as residents and visitors return to their homes and places of lodging the roads become congested and traffic at key intersections exceeds maximum capacity. The problems of excessive traffic are compounded by oversized vehicles, including mobile homes, boat trailers, and other recreational vehicles, which have trouble navigating the narrow lanes and tight curves of the mountainous terrain. Congestion increases the time that vehicles are idling, contributing to regional emission problems. It also detracts from the visitor experience as the ability of visitors and residents to move predictably throughout the park and local communities is compromised. Finally, congestion threatens visitor safety as motorists try to navigate the difficult traffic conditions while remaining alert to the proximate pedestrians and bicyclists.

In addition to the limitations of the local road network, MDI is significantly constrained in its ability to offer adequate parking during the peak summer season. Acadia National Park has one main parking area, which is located at the Hulls Cove Visitors Center, and several smaller parking areas located at the most popular sites within the park. However, all of these parking areas cannot accommodate the automobiles of every park visitor. Many of Acadia National Park’s parking areas are very small, in some cases accommodating as few as six cars. What’s more, many parking areas serve multiple purposes, including acting as scenic overlooks or staging areas for one or more trails. Consequently, the park has experienced substantial overflow parking along the shoulders of roads and in the right lane of the park’s historic loop road. Overflow parking detracts from the visitor experience and the park’s scenic beauty, adversely impacts natural and cultural resources, and affects the safety of motorists, bicyclists, and pedestrians.

Demand for parking in gateway communities also often exceeds supply, especially during summer months. By local ordinance, all places of lodging in the area are required to provide sufficient parking for their guests. However, this does not help the park’s many day visitors. The towns themselves maintain municipal parking areas and curbside parking, but both are limited and in demand.

It is important to note that automobiles are not the only modes of transportation creating the transportation-related challenges at Acadia National Park. Sitting along the coast of Maine, the park is also accessible by water and a popular stop for cruise ship operators. On a single holiday weekend, cruise ships may bring more than 10,000 visitors to the area. The vast majority of these visitors will not have a vehicle of any kind. Having an efficient way to move these visitors throughout the area is important, both to enhance the visitor’s park experience and to balance travel demand at key sites (including the Bar Harbor downtown) so that no one site is overwhelmed with use.
The system, which began operating in 1999 with six buses, is now comprised of 17 shuttle buses that in 2001 carried nearly 240,000 passengers. The Island Explorer is one of the most successful alternative transporation systems within NPS. The Coalition for Sensible Energy reported that, in its first year of operation, the system replaced nearly 43,000 cars and recreational vehicles on MDI, effectively eliminating two tons of pollutants that create haze.

The Island Explorer is available not only to park visitors but also to area residents and other visitors. Although available to everyone, the Island Explorer is not mandatory for anyone; park visitors and area residents alike are permitted to bring automobiles onto MDI. Riders are not required to pay a fare to board the shuttle.

While it was established to carry park visitors and thus relieve congestion in the park and surrounding areas, the Island Explorer is providing an unanticipated benefit—serving local residents. In 2001, 22 percent of the Island Explorer riders were residents, and that percentage is expected to continue to rise. These riders include local employees, particularly those who work in the tourism-related industries of lodging, food service, and small retail. The system has also become a significant mode of transportation for local youth, allowing them to move around the island safely.

During its inaugural season in 1999, the Island Explorer carried over 142,000 riders. In 2000, nine buses were added to the system, and the number of routes was increased from six to seven. Ridership for the next two seasons increased first to 193,000 and then to nearly 240,000. In 2002, the Island Explorer carried a record-breaking total of 281,142 riders—an 18 percent increase over 2001.* The four-year trend represents a 107 percent ridership increase.

The Island Explorer contributes to the park visitor experience, the environmental quality of MDI, the safety and comfort of both citizens and visitors, and the state tourist economy. For example, in 2001 more than 200,000 visitors rode the buses, keeping approximately 88,000 vehicles off park and MDI roads. As a result, emissions of carbon monoxide (CO) were reduced by 33 percent and emissions of volatile organic carbons (VOCs) were reduced by 25 percent. What’s more, the Island Explorer reduce nose near park roadways by 6.3 decibels – the same reduction that would result from building a 12- to 15-foot-tall noise barrier along a road.*

The Island Explorer contributes to the park visitor experience, the environmental quality of MDI, the safety and comfort of both citizens and visitors, and the state tourist economy. For example, in 2001 more than 200,000 visitors rode the buses, keeping approximately 88,000 vehicles off park and MDI roads. As a result, emissions of carbon monoxide (CO) were reduced by 33 percent and emissions of volatile organic carbons (VOCs) were reduced by 25 percent. What’s more, the Island Explorer reduce nose near park roadways by 6.3 decibels – the same reduction that would result from building a 12- to 15-foot-tall noise barrier along a road.* More buses will be purchased in 2003 to support additional ridership, and a new storage facility for vehicles may be leased or constructed. Acadia NP is also considering the possibility of constructing a second visitor center, which would include sufficient parking for daily visitors and a pick-up/drop-off point for shuttle buses. Acadia NP and its partners expect to have more riders—and subsequently more buses—in the future. As a result, the Island Explorer will continue to ease pressure on local natural resources.
Partnerships between Acadia National Park and other stakeholders yielded particular benefits without which the Island Explorer likely would not have succeeded. Partnerships produced the financial support necessary to plan the system, purchase the first fleet of buses, and operate the system for four years without making service mandatory or requiring riders to pay a fare. A diverse team, including NPS, USDOT, Maine DOT, town governments, the Friends of Acadia (FOA), and a myriad of other public and private organizations came together to create and support the Island Explorer, which has altered the experience of visiting MDI and Acadia National Park.

The regional transit system produced through partnerships also fostered operational efficiencies that would not have been possible with multiple, parallel systems. Partnerships also made technical expertise at each phase of the system’s evolution possible as NPS was not required to provide this element alone. Finally, partnerships have been essential in generating the kind of widespread public support that removes potential barriers before they are established and helps keep an alternative transportation system afloat.

Recognizing their interdependence, Acadia National Park, Maine DOT, MDILOT, and other partners adopted a regional perspective on developing transportation solutions. This perspective led the partners to create a single transit system that serves both residents and visitors to the park and local communities. This single system provides transportation solutions with greater efficiency and a higher chance of sustainability than systems serving park visitors and community residents separately could. While institutional cooperation has been vital to the success of the Island Explorer, personal relationships among partners have also been important in fostering the speed and relative ease with which the system has been established. In many cases, leaders in MDI communities, at the park, and at state agencies had worked together on previous transportation and planning projects. The strength of these personal relationships produced an atmosphere of personal trust and respect, fostered efficient communication, and helped the partners surmount potential barriers between institutions and agencies.

Local Champions
The Acadia National Park deputy superintendent has been a key player in the Island Explorer’s evolution, having been personally involved in the planning and development of the system throughout his time at the park. The deputy superintendent represents Acadia National as a voting member of MDILOT and works cooperatively with town representatives and other local stakeholders to help devise transportation solutions for MDI. He also initiated planning for the Island Explorer using the park’s 1992 GMP, which included funding for studying the feasibility of developing an island-wide transit system.

The success of the Island Explorer is due not only to the leadership of the Acadia NP deputy superintendent, but also to the vision, energy, commitment, and local expertise of a local project champion. In the case of the Island Explorer, the project champion was a local transportation planner who was the first manager of Downeast Transportation, Inc. (DTI) and a council member for the town of Bar Harbor. MDILOT hired him to plan the Island Explorer using the Acadia NP concept as a starting point. As a resident of the region, this individual had a high level of trust and credibility with key stakeholders. This benefit was compounded by the individual’s understanding of the potential for public transit on MDI. Due in part to his stake in the community, this individual brought the kind of energetic commitment that is needed to see a project through its inevitable ups and downs over many years. This local project champion is still involved with the system and continues to participate in stakeholder meetings and planning sessions. A local transit planner emerged as the Island Explorer’s project champion, providing vision and energy in partnership with Acadia NP, the Friends of Acadia and the MDI League of Towns.

A strong park friends group has also supported the Island Explorer. Established in 1986, FOA is a powerful advocacy group with strong, long-standing financial support in the community. The commitment and resourcefulness of FOA have been essential to the system’s development and financial sustainability. In 1997, FOA enabled a critical test of the market for a transit system when it subsidized operation of the campground shuttle so that the $2 fare could be eliminated. The success of eliminating the rider fare (ridership jumped 600% the year after the fare was eliminated with no change to the service or route) encouraged Acadia National Park, MDILOT, and other partners to pursue planning and implementation of an island-wide transit service. FOA has provided financial support for the operations and maintenance of the Island Explorer during its first four seasons. Most recently, FOA helped the system move toward long-term sustainability when it negotiated and received on behalf of the Island Explorer a $1 million donation from L.L. Bean. The donation, which FOA secured with its own funds, will be used primarily to extend operations from Labor Day through Columbus Day, beginning in 2003. Finally, FOA has been a prominent and passionate advocate of the Island Explorer, providing information and promoting the system in communication with its members, in meetings with the community, and on the FOA web site.
While the Island Explorer has benefited from the involvement of key state and Federal partners, its success is due in large part to the involvement of local individuals and organizations. Local residents, organized by MDILOT, have led system planning, contributed financially to operations and maintenance, and received annual public updates on system performance. Local support not only attracts funding but also helps to make the system viable over the long term as NPS units respond to local needs and meet local expectations.

MDI communities and local stakeholders (including FOA) managed and funded the planning of the Island Explorer. Individuals and groups working on MDI and within Acadia National Park developed the mechanics of the system, including hours of operation, routes, and individual bus stops. As a result, system characteristics have stayed close to the needs and preferences of the local communities. MDILOT was central to this effort. A non-legislative body, MDILOT is comprised of the managers of the four island towns, one representative from Acadia NP, and one representative from each of the three communities that surround MDI. MDILOT functioned as a mechanism for town leaders to discuss and do system planning. As a public body, MDILOT also provided a forum for public input and outreach. Finally, MDILOT brought together the various communities, thus providing Acadia NP with a single local governance organization with which to work.

Each of the four towns on MDI contributes financially to the Island Explorer, and each must receive annual approval from its town meeting members before it can commit funds. Local financial investment helps not only to support the system but also to demonstrate local commitment. In this way, local financial support represents local popular support for the Island Explorer, a key component of its success.

The Island Explorer has been able to document its growth and success through regular gathering and sharing of system performance data with stakeholders and the public. Collecting and disseminating reliable information about the system’s ridership, rider demographics, and on-time performance have multiple benefits, including attracting financial and political support from local communities and state and Federal agencies. In addition, partners can make informed modifications to the service based on these data, rider surveys, and local input.

The Island Explorer Development Timeline


Acadia National Park adopts a general management plan (GMP) that recommends that the National Park Service (NPS) work with Mount Desert Island (MDI) municipalities and others to implement an island-wide transportation system. The GMP includes a system concept that is based on a feasibility study.


Downeast Transportation, Inc. (DTI), a non-profit transit provider operating in the region, introduces seasonal shuttle service between local campgrounds and Acadia NP. The system has one route and is supported by Congestion Mitigation and Air Quality Improvement (CMAQ) funds. Users pay a $2 fare to ride.


Congestion problems in MDI communities become severe enough that the Mount Desert Island League of Towns (MDILOT) begins to explore options. As a voting member of MDILOT, Acadia National Park participates and presents the transit concept from its GMP as a possible solution.


MDILOT submits an application for funding of an island-wide transit system to the Maine Department of Transportation’s (DOT) T2000 Program, an initiative designed to encourage innovative local transportation projects.


With financial support from the Friends of Acadia (FOA), DTI eliminates the $2 fare for riders on the campground route. The system experiences a 600% increase in use, from 3,000 riders in 1996 to 12,000 riders in the first year of fare-free service. Maine DOT awards funding to the Island Explorer Shuttle Bus System (Island Explorer) project through the T2000 Program and includes the proposed system in its biennial transportation improvement program (TIP). Acadia NP and its partners begin working closely with Maine DOT in order to implement the approved system.


Maine DOT purchases eight propane buses with funding from the Federal CMAQ program, a local match provided by Acadia National Park, and a NPS grant.


DTI begins operating the Island Explorer on six routes from June 23 through Labor Day. Operations and maintenance funding is provided by the CMAQ program, Acadia National Park entrance fees (through the NPS fee demonstration program), FOA, MDI towns, and businesses with shuttle stops. The system remains voluntary and without fare and carries more than 142,000 riders in its first season of operation.


The Island Explorer expands to seven routes in 2000. Nine buses are added, purchased by NPS with funds procured through the NPS Alternative Transportation Program. The buses are loaned to the Maine DOT through a cooperative agreement with NPS. In its first three years of service, the system experiences a 75 percent increase in ridership, with the largest increases on routes that serve campgrounds.


L.L. Bean pledges $1 million in the form of a qualified sponsor agreement to support the Island Explorer. FOA is the designated recipient of the funding, 99 percent of which will support system operations in order to extend service past Labor Day to Columbus Day.

Acadia National Park

Last updated: March 31, 2022