In this screenshot Lara is standing on the ledge with the Medi Pack. Drop into the water again, swim to the exact opposite side and climb onto the greenish ledge (1). Climb up the ladder (2) and back flip onto the ledge behind (3). Walk to the front left corner of the ledge (towards the ladder), turn left 45 degrees and take a running jump to the ledge on the left of the ladder (4). Now jump to the block on the left (5) and turn around. Take a standing jump to grab the ladder (6) and climb to the top (7).

Take a running\ standing jump to the next ledge to the right (or to the left if you face the pool - 1) and then a running jump towards the ledge with the cobra (try to land on the left side - 2). Kill it and walk to the other side of the ledge. Take a standing jump to the next ledge that is close to the doorway (3).