Yap
Yap is the most "off the grid" of the big three Micronesian islands (Palau, which technically is its own country; Chuuk/Truk and Yap), but that means it is also the destination that has retained its historical charm. It is not over-developed, and I imagine it is similar to what Palau was like 30 years ago. The marine conditions in Yap were calmer with less currents than in Palau. Highlights in terms of marine life are almost-guaranteed manta sightings and mandarin fish mating--the latter of which is always a sunset dive. Topside highlights include cultural activities with the native Yapese population, and learning about their ceremonial stone money.
