Hi Anniepans- welcome to the forums!
If you have not looked at Dr. Craven's PDA, It might not work. A lot of things are triggered by other actions.
The locker number is 13 and the locker combination is R4 L2 L7 R9- you have to click the button in between each number.
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You need to rent the snorkeling equipment in order to do the water maze- then click on the eel, go through entrance, shark, turtle, octopus, porcupine fish, crab, urchin and manta ray. The current will suck you to the next animal after each correct click. Again, this may not work if you have not found the clues for this puzzle