Gollum's boat??

[TheGreatElvenWarrior]

Originally Posted by Bêthberry

And its sails were made from balrog wings!

Seriously, though, it could have been a coracle, made from skins and willow wands and fat.

Do you think that the goblins threw things that they didn't need into the cave such as broken tools or unneeded things that Smeagol could make a boat out of. His boat was most likely made out of a bunch of random junk that he found.