The floor of the Gulf is flat and desolate like a sandy desert.
This gives the fish a place to hang out.
Where the bottom doesn't have any place in the sunlight for corals to adhere, they cannot grow. No corals, no higher forms of life.
The ship provides a gazillion places for all manner of life to find a place to anchor, thus providing the basis for a whole ecosystem of life.
It also makes a fun place for recreational diving.