Possible Leads
From M2K2: Metroid Prime 2 Wiki
Found by: Ghost, Madrox
In Venomous Pond, there is a Dark Temple Key that you 'need' Grapple Beam to get... Bzzt. Wrong!
Near the Save Station there are 3 Ingsphere Caches. You will need to practice L-Lock Jumping before doin' this simple trick succesfully.
After looking as far down as you can, hop onto the Biggest cache, and just jump to the key.
