Great Isaac, a 19th century English lighthouse, lies approximately 20 miles north of Bimini. Erected in 1856 as an aid to navigating the local waters, it now stands as a monument to Bimini's past. The boat ride is about 45 minutes long, passing through the heart of Bimini's "dolphin grounds." Once there you are free to explore the island including the ruins of the former lighthouse keeper's residence (the light is now automated). The shoreline also provides an excellent snorkeling opportunity. The entire trip takes about four hours and moderate agility is required for getting ashore.