For one scene, Thomas Jane had to swim alongside a real live shark. He was only allowed to shoot this once he had completed all of his other scenes.
(at around 9 mins) The license plate pulled from the shark's teeth is the same one found in the tiger shark in Jaws (1975).
This was the first movie Stephen King saw after his nearly fatal encounter with a van. He stated "My first trip after being smacked by a van and almost killed was to the movies. I went in my wheelchair and loved every minute of it."
Samuel L. Jackson happily signed on for the film, as he had enjoyed his experience working with Renny Harlin on The Long Kiss Goodnight (1996).
(at around 50 mins) The Gen 2 Mako is described as 45 feet long and 8,000 pounds. That would make it more than three times the length, and four times heavier than the largest Mako shark ever recorded, and twice the size of the largest known Great White Shark.
Renny Harlin: (at around 11 mins) As one of the workers of Aquatica who are heading home for the weekend on the supply boat.
Renny Harlin: [Finland] There is a small Finnish flag in Janice's (Jacqueline McKenzie's) room. In the kitchen, there is a dry-erase board with a shopping list, and the first item on it is "Finnish pancakes." Helsinki (Finland's capital city) is also mentioned. Finlandia vodka, drunk in some shots, also comes from Finland.