Level: 09. Tomb of Tihocan
Artefact 1/2. You're in the huge room, full of water. When you open the bar in the flooring and gain a raft, get on the upper level of the chamber.
Go to the niche with movable gear. Grab the bar and move the gear round. The water will fill the room. Jump into the water and swim to the platforms, which are near the niche with three carved heads. Dive there.
Inside one of the pillars is gear with the lever, switch the lever - the bar in the flooring will open.
Surface, take a breath and dive again. Swim to the niche, where is just now open bar. Pick up Artefact 1/2. Back to the platforms.
Artefact 2/2. After leaving the huge underwater room you will come to the underground cave. Before you will go to the Tomb of Tihocan you must find an underwater gear, which is opening the entrance gate. Dive.
Swim to the left. There is a platform from where take ammo. Near the platform is niche - swim inside and take Artefact 2/2.