There are four National Natural Landmark sites on Guam. Natural features represented include a remnant of a great caldera, evidence of pillow lavas, intersecting dikes, and a massive sea stack of black coralline limestone. All four sites were designated as NNLs in 1972, ten years after the National Natural Landmarks program was established. Sites range in size from 28 acres to nearly 525 acres and are owned by the Government of Guam and/or private individuals.
Below is a map of sites in Guam.
Please remember, National Natural Landmarks (NNLs) are not national parks. NNL status does not indicate public ownership, and many sites are not open for visitation.