Full Health

While playing a game press select, Up, Left, Down, Right, Up, Up, Down, Down, and Circle, Circle

All Weapons

While playing a game, press Select, Down, Down, Left, Right, Left, Right, Up, Up, and Square, Square

Unlock Everything

At the main menu,hold select and press Left, Right, Up, Down, Circle, Triangle, Square, and X

BMF location

In deathmatch:lobby...Go upstairs and grab the rocket launcher, now go to the wall facing the lobby (youre still upstairs) start blowing up the wall and make a hole to the roof! where there is one of those BMF's at the top!

Secret Rooms

In the lobby, as you go up any ramp, blow a hole in the wall with a rocket launcher wherever there is writing on the wall. There will be a secret room in each writing spot. there are two flamethrowers, a rail driver, and a fusion rocket launcher.

Third level in lobby

In the lobby multiplayer level, you can reach the third level of the lobby (the roof) by blasting through the wall of the ramp.  There is a railgun and fusion rocket launcher up there.  You will know if it is the right side of the roof if you can see arches on the other side of the wall.

Extra Sub

After you`ve gotten to the Sub Bay and encountered the fist enemy sub in the area where there is a round hole in the floor. Stop over the hole and look around when you see a crack in wall blow it and go in side, at the end of the tunnel there is a cave and in that cave there is an extra Sub with 700health and 20torpedoes.

Hidden Pit

In the deathmatch:Installation XJ5, you can get outside to the pit! here is what you do Grab the rocket launcher and jump down turn left...see the archway above?
Blast a hole in the wall below the doorway and start building a tunnel stright to the open window One might ask why do all this work when you can just go to the archway above and start blasting around the window? Well it doesn't work for some reason...there is like an invisible wall which wont let you pass Once you make the tunnel all the way through, you can look down into the pit below.
If you drop down, you will always die! Turn to the left or right and blast a hole big enough to jump into (you make the hole on the outside of the wall) Jump into the hole and then make another hole straight in front of you but down a little ways.
Now that you have made another hole, jump into it Make sure the hole isn't to far down or you will die from the fall Repeat this process until you have reached the bottom of the pit. Remind you that it is next to impossible to get back up once youre down there