Deep Blue Sea

The following weapons appear in the film Deep Blue Sea:

Deep Blue Sea (1999)

Mossberg 590 Mariner

Carter Blake (Thomas Jane) pulls a Mossberg 590 Mariner shotgun with a pistol grip, folding stock, and high-capacity magazine tube from a case in the aquatic lab during the first attack by one of the sharks. He chambers a round but doesn't get a chance to fire the weapon.

Mossberg 590 Mariner 12 Gauge

Carter Blake (Thomas Jane) takes the Mariner out of the cabinet.

Carter pumps the action of the shotgun.

Heckler & Koch P2A1 Flare Pistol

At one point in the film a member of the lab's staff, Brenda Kerns (Aida Turturro) fires off a pair of Heckler & Koch P2A1 Flare Pistols when the staff hold a surprise birthday party for Dr. Susan McCallister (Saffron Burrows). The black powder from the remaining flares is then used to create a makeshift bomb as described below.

Heckler & Koch P2A1 Flare Pistol 26.5mm

Spear Gun

A spear gun using the stock and reciever of a Remington 700 rifle is seen being used by Carter at the start of the film to capture an escaped shark from the research facility. It is then used by Sherman "Preacher" Dudley (L.L. Cool J) at the climax of the film to shoot the last of the sharks, the spear having a makeshift bomb made using the black powder from several flare gun cartridges. The steel cable trailing behind the spear is then put to a car battery, the electric current setting off the bomb and killing the shark.

Carter Blake (Thomas Jane) shoots a spear at the shark in the beginning of the movie.

One of the spears hits the shark in the beginning of the movie.

Extra

The spears makeshift bomb is constructed from flare gun cartridges. The cartridges are disassembled and the black powder is poured into one of the original spears. The spear has a steel cable attached to it and when it's connected to a car battery the bomb explodes. Carter Blake (Thomas Jane) is seen making the bomb in the movie.

Carter picks up a spear and opens it up.

Then he disassembles a flare cartridge, as also evidenced by the ammo box in the screencap below.

After that he pours the black powder into the spear.

Ta-daa! The makeshift bomb is ready, and Carter loads his speargun.

Carter Blake showing Susan that when the cable is connected to the car battery, the makeshift bomb at the end of the spear will detonate.