None of the above.
Platypuses do not actually live in any waterholes or creeks. They dig burrows in the banks of freshwater rivers and creeks. They can be found alongside creeks or rivers with a slow rate of running water, as well as in still freshwater ponds, dams, lakes and billabongs - as long as there is a bank high enough above the waterline for the platypus to dig its burrow.
Platypuses will never be found in any marine or saltwater environment such as oceans,