Help: Rocktropia Lockpick Kit VI

[Smartiez]

Currently doing a returned Lockpick Kit VI but atm I'm at the water with the Rippers in. Just before that I still need to place a Dynomite but can't find it. I think I need a key to open door behind water first. Anyone recently did any of these lockpicks? (Still got 2hrs )

need last dynomite or key but can't find either.

 

[aia]

Currently doing a returned Lockpick Kit VI but atm I'm at the water with the Rippers in. Just before that I still need to place a Dynomite but can't find it. I think I need a key to open door behind water first. Anyone recently did any of these lockpicks? (Still got 2hrs )

need last dynomite or key but can't find either.

as for the key, I think I read somewhere for at least one of those missions, there is a key right under the waterline.