Touring El Malpais requires preparation. Bring the right vehicle; if you plan on exploring the more remote sections of the park, a properly equipped four-wheel-drive vehicle with high clearance is suggested. Gear and clothing should be matched to the season of your visit.
Your safety is your responsibility here as well. Given the long distances and difficult terrain, it can be a while before help can reach you. Bring the gear you'll need to have an enjoyable and safe trek.