Preparation

Ready the machete, so you can free yourself from any unwanted passengers. These will try to pull you under water. On the left you can climb out onto the shore. Collect the big harpoon gun, ammo for it and some explosives. When picking up the harpoon, read the displayed message carefully, it tells you how to aim at the kraken. You can also get another oxygen bottle there. In the building below you, under water, you can find a small medipack in the lower passage at the back.

Attacking the Kraken

Now it's time to attack the kraken. Ignore the jelly-fish as much as possible. Don't forget to catch some air now and then. When swimming towards the kraken, shoot a few of them, using the harpoon, but then use the button that was mentioned when picking up the harpoon to aim at the yellow spots at the kraken. All the while struggle against the jellyfish pulling you down. When the kraken is hit it will retreat.

Placing Explosives

Then you have to place a charge at one of the pillars. If you are quick and find the time, you might even place to on neighbouring pillars.

Afterwards take a deep breath and repeat the procedure, till all four pillars have been hit. Do not forget to collect new charges outside, after detonating two of them. If you run out of harpoons, there are some more by the sunken temple on Indy's side.

When you have hit all four pillars, they will collapse. The Kraken will retreat and the water level drops. Run up towards the pedestal in the middle and pick up the artefact. Now off to Hong Kong.