HIDDEN GROTTO

The cave entrance is a vertical, underwater shaft, located in the lake at (55.2, 65.9). The shaft is just large enough for a Rock Drake to fit through and there is space to park 3-4 drakes once through the tunnel. You won't be able to take the drake far into the cave system, but it's a convenient way to get there.

There are a number of vertical cliff climbs in this cave that you will need to traverse to get to Artifact of the Shadows, which can be overcome with Climbing Pick and/or Zip-Line Anchor (don't forget Zip-Line Motor Attachment to get back out)

There are also several longer underwater tunnels, full of aggressive creatures. It is suggested to take multiple sets of SCUBA Armor, a Harpoon Launcher and plenty of Spear Bolts or some other ranged weapon (e.g. Crossbow) that can be fired underwater, is recommended over melee weapons due to the presence of Electrophorus, Cnidaria, and Baryonyx.

Bring a Campfire with some Wood when traveling through the cave; it is extremely likely you will be Lamprey'd in the underwater tunnel, making you a target for the swarm of Seekers that surround Artifact of the Shadows. Keep your wits about you in case of an Earthquake; if climbing out of the water, time your movements so you don't fall back into the water.