tomb raider III - ps1
  • in the "antartica" level, i
  • From what i can gather from reading a walkthrough you are only to enter it from one way to progress. Here's a clip from that walkthrough from the beginning of the level as you escaped the sinking helicopter:

    Just to the left in the water are some Desert Eagle Clips. If you're brave
    (or low on ammo) you can go get them. Jump to the small ice island out front
    and then turn towards the ledge to the right. Jump in the water and quickly
    swim around it to the left, where you can climb out on the slope. Move
    forwards past the hut and take a running jump to the ledge on the other side
    of the channel. Turn right and climb up the ledge. Follow this up to a slope
    and use a standing jump forward to get atop it. Jump to the snowy arch and
    cross it to the cave. Jump inside for a Large Medi-pack, Flares, a Rocket,
    and a Save Crystal. Return across the arch and head to the left, around the
    corner. Jump to the ledge below and follow it to the end.

    Swim across the water to the ledge just ahead. Climb and wait for the
    exposure meter to fill up and then jump in the water again. Swim to the low
    ledge ahead near the ship and climb out. Climb up the nearby ledges and grab
    hold of the ceiling. Swim to the end and drop down on the block. From here,
    you can jump to the ship.