What the heck is this?

How often does that area flood? Tie it to a tree after plugging the hole (stick with a rag or other chunk of wood) then float it to a loading area.

 

You have a 1950s hot water tank.

 

But did you kill any ducks??

ncb

 

Did you get it out?

 

Have you shined a light into the tank to see if it's just an empty tank or does it have stuff inside?

 

I think you're on the right track, but I'm betting the actual manufacture date is earlier still - like the 20s.