Assassin's Creed IV: Black Flag - Smuggler's Dens: Anotto Bay

Anotto Bay is a Smuggler's Den, but you can reach it via an underwater passage, accessible by the diving bell route. There are sharks in the way, but the den itself only has human enemies. However since you get to it through the underwater path, you have no weapons when you get there, so you need to use mainly (although not exclusively) stealth to navigate it. *There is an Assassin Contract that will also direct you to the same place; you can combine all activities and visit Anotto Bay only once so as to complete the contract as well, but I prefer going for the contract independently of the site's exploration, because the contract has an optional objective that is not always easy to complete if you are doing a full exploration of the den at the same time.