How to reach the top of the waterfall on Pokitaru in Ratchet & Clank
Near the end of Ratchet & Clank, the titular heroes receive a call from an old friend to help clear out the Blarg from a peaceful planet known as Pokitaru. As you traverse the planet, killing Blarg and restoring the peace, an optional objective will appear, telling you to reach the top of the biggest waterfall on Pokitaru.
At first, this is one of the more confusing tasks to complete, but once Ratchet receives the proper gear, you'll be able to reach the top of the waterfall faster than you can say Sheepinator.
The first thing you MUST do is get the O2 mask by cleaning up the pumping stations after you destroy all the Hydroharvesters on Pokitaru. Once you clean up the station, the O2 mask is yours to keep, allowing you to breathe underwater for however long you'd like.
Then, head back to your ship, and follow the path straight until you reach a body of water in front of you. Jump in and swim to the point marked on the map above. Dive underwater and you will see a cave with a whole bunch of explosive boxes by the entrance.
Follow the secret passage and you'll eventually emerge in a cave near the top of the waterfall. Use the platforms to escape, then grapple across the gap to the other side. The path from this point on is pretty straight forward, although you will have to fight quite a few enemies in order to clear the way.
When you finally reach the top of the waterfall, you'll be greeted by a Telepathapus. Once you take down the Telepathapus, you'll receive a gold bolt to add to your collection. Don't take too long to celebrate though, the Galactic Rangers are waiting!