Are there great whites in the Caribbean sea?

Not usually, although you never know because the biggest Great White was caught in Cuba which is not far from Puerto Rico.

The sharks that usually live in Puerto Rican waters are :

Hammer Heads, Caribbean Reef Shark, Nurse Sharks and the two most dangerous... the Bull Shark & the Tiger Shark.

But don't be scared! The last fatal shark attack was in 1922 off the coast of Santurce, Puerto Rico. After that there have been about 5 more minor shark attacks