Re: Pressure treated lumber for swim raft?
Yup. Had a PT floating dock lasted for years and still in service now by another to whom I gave it. Ditto for a floating duck blind.
Note: Environmental regs around here no longer allow PT for docks, water structures etc; pre-existing stuff is grandfathered, but new builds are forbidden. Have to use "plain" rot resistant woods for piles, docks, floats, bulkheads, i.e, expensive tropical hardwoods. So you might want to check regs for your area.
This new ship here is fitted according to the reported increase of knowledge among mankind. Namely, she is cumbered end to end with bells and trumpets and clocks and wires. It has been told to me she can call voices out of the air or the waters to con the ship while her crew sleep. But sleep though lightly. It has not yet been told to me that the sea has ceased to be the sea.--Rudyard Kipling