How deep does a .357 Magnum penetrate Water?

At the muzzle, a representative .357 Magnum load penetrates approximately 1075 mm (42.3 inches) into water.

What is the impact energy of a .357 Magnum?

This .357 Magnum load carries about 796 joules (587 ft-lb) at the muzzle.

Penetrates to ~42″ before stopping

Penetration depth

1075 mm (42.3″)

Impact velocity

395 m/s (1296 fps)

Muzzle energy

796 J (587 ft-lb)

Bullet behaviour

Expanded

Fired at the muzzle, a representative .357 Magnum load (10.2 g, SP, 395 m/s) reaches roughly 1075 mm (42.3 inches) into water.

Water is a dense fluid medium; bullets destabilise and shed velocity quickly.