Pirate island

[holyhalo]

Hidden Pirate island. I'm trying to build some sort of a city on the island that is made up of broken boats and re purposed parts of ships that have sunk around the ring surrounding the island. It is supposed to be a pirate hideout for when things get too hot. The island is big enough to supply living space for several 10.000 people.

The surrounding rock ring is uninhabitable land and nearly impossible to traverse on foot due to the spikey, sharp features of the ring. And the fact that it is a breeding zone for all sorts of human eating volcano monsters.

I'd like to make it look something like this. It's volcanic in nature, created by what used to be a highly active volcano thousands of years ago. The island in the middle is all that is left a piece of space debris that decided the volcano was as good a target as any.

So, as for my questions. How would I go about creating a city on an island like this? And how do I make the ring more... sharp. At the moment it looks nice and elevated but it doesn't say deadly spikey. And last one, for now, is there a good way to create rocks sticking out of the ocean? Like dangerous for wooden ships and such?