You need the rope ascender to access this tomb. Run past where Jonah is sitting and around the dune. Use the rope ascender to bust open the door and enter the bunker. Follow the tunnel and use a rope bridge to get across the water.

You will enter a room with the Temple of the Handmaidens camp. Start by cranking the gear to let the buoy out. Run to the left and climb up a short ledge. The buoy will turn a pole your way. Jump onto it and use it to swing over. Yank out your bow and shoot a rope arrow at the coil below you. This allows the buoy to push another pole your way. Jump on and then over to a craggy wall. Use your climbing axe to hold on and climb up.

Claim your reward at the back of the tunnel.

The Flooded Vault Temple of the Handmaidens None
Tomb Raider (2013) Challenge Tombs

Tomb of the Lost Adventurer DLC · Tomb of the Unworthy · Halls of Ascension · Well of Tears · Chamber of Judgement · Stormguard Sanctum · The Flooded Vault · Temple of the Handmaidens