Rangiroa is an atoll; a much older island compared to Nuku Hiva. I invite you to read the volcano island geology history section of the Atoll and Coral Reef wiki pages to understand how the islands age. Somewhere in the lagoon is a slowly sinking seamount.
A cool thing about Rangiroa is the cruise ship actually enters into the lagoon. Since Rangiroa is a main cultured black pearl location, I’m sure there are strict environmental rules. The Silver Whisper uses its own life boats to act as tenders to shuttle guests to/from the island.
Such a small, remote island does not allow for much tourist stuff, but I visited a black pearl farm (Gauguin‘s), and I found the biology and craft fascinating. Cultured pearls start with a seed, called a “nucleus”, that is implanted by “grafters”. Black-Lip Oyster shells are too thin, so other shells are used – in the past mollusks from the Mississippi. 18-24 months later they are harvested. The oyster stops growing a pearl at that time, but a new seed can be placed to grow an even larger pearl.
Black-lip Oysters can support three pearl harvesting cycles, each cycle being 18-24 months. Other oyster varieties can support up to ten cycles. There is an annual auction where black pearls are sold to wholesalers (and to tourists year-round).
Near the gangway there is a model of the ship. I circled about where my cabin is.
Tomorrow: dolphins!