Double Reef - Guam is a northern boat-only reef dive with a healthy coral face, clear water, and plenty of schooling fish. The site is easy enough for new divers and snorkelers, but it still rewards patient reef time with reef sharks, turtles, barracuda, and the occasional spinner dolphin pass. Plan on a calm-day boat run from the island's north side rather than a shore entry, and treat it as a relaxed reef dive with normal open-water checks before entry.