As promised by Mo, the Volcano has many pearls inside; though all are guarded by Vorax. The Beluga is required to access the Volcano, which is located atop the Black Isle.
There is very little difficulty in taking all of the pearls, as Vorax are not exactly challenging and there is little puzzle to progress through the Volcanoes innards. A large amount of pearls can be found here, a total of fifteen! Each pearl is held by an individual Vorax and needs to be released and collected individually. The exception being if loose pearls are in close proximity when picked up, in which case all will be collected simultaneously. The whole area is more of an easter egg and reward for obtaining the working Beluga. Still, this is definitely in the players best interest to explore, just for the rewards sake.