There’s a book about sportfishing around rigs in the gulf. It was on my reading list long ago and I never got around to it but it claimed they caught large things which have never been seen before. I vaguely remember some of them diving near rigs to get a closer look and said it was one of the most dangerous thing they ever did.
Edit: I remembered it differently but the book is called the helldiver’s rodeo about oil rig spearfishing in the Gulf of Mexico:
The Helldivers' Rodeo: A Deadly, Extreme, Scuba-Diving, Spear Fishing Adventure Amid the Offshore Oil-Platforms in the Murky Waters of the Gulf of Mexico https://www.amazon.com/dp/1590770056/ref=cm_sw_r_cp_api_8HoDAbNP2HMKY