Welcome to the first level ... and to the beautiful Mediterranean Sea. I bet you'll spend some time admiring Lara's outfil .. especially in the cinematic .. so take your time.
And yeah, Lara is much more sexy in this game.
When you're done drooling, just jump into the water. You can kill the sharks using your pistols or even better the speargun (yeah, Lara finally figured out how to use the pistols under water).
Use your sonar to find the entrance to the big ... rock thing under the water, you should find it pretty much to the opposite side from where you start the level. There are 2 entrances though, one to the main big rock and one (just next to it) for a much smaller one. You should enter the small one first.
If you enter the large cavern you will need to get out and enter the small one after.
Right, I assume you go in the small one now. Use F to get some light into the room, it will really help .. and make your video card cry.
Just follow the path and avoid the jelly fish, at the end of the cavern you will find the first axle. Grab it using E and head for the big cavern.
Get into the main/large cavern with the axle in your hands and put it in either right or left wheel center. You will find a second axle on a table in the same room, put that one in the other center.
Now, you can turn the wheels in order to complete your first puzzle. The goal is quite simple, have the parts with cercle inside in the top wheel. Just look at the image to get an idea.
When they're in the right position it will open up ... and you can swim through. Quite cool really. Follow the new channel and get out of the water. Time to watch Lara nice and wet ..
Ok, time to snap out of it and get back to action ... yeah, bad word for it, I know. Anyway, head through the tunnel.
Use the block ahead to climb - you'll find a health pack on it too. You don't need to jump and grab the ledge if you're not looking for the artifact, but then again, it is fun.
Use the ledges to get higher.
Jump up and Lara will sit on the last ledge, from there you can get to other ledge on the right.
Follow the path marked and get to the pole, use that to swing across.
There should be 3 poles, swing from one to another.
You should find an artifact in a jar over there, grab it and continue to the ledge ahead.
Get back down and continue towards the door and switch.
Grab the two small boxes and position them on the left pad.
Get in front of the other pad and use the grapple on the hook, the dragon/snake head will fall and keep the second pad activated. The position is quite important otherwise the grapple won't work!
Use the middle switch now and tada ... the door will open.
Enjoy the cinematic and head for the next level: Nifleheim.