Ah yes, I remember this well. Just to clear some bits up in the story bit:
>The theme park was Chessington World Of Adventures (or just Chessington, tbh), and the ride itself was called Dragon Falls (not to be confused with Dragons Fury, a rollercoaster at the same park).
>The boats themselves were shaped more like little wooden boats with flat bits at the front. There weren't really any proper seats as such, just some grooves where you shove ya feet in. There WAS a tunnel shaped like a dragon on the outside though, although on the inside it looked like... a metal storage container. Effort much?
>You should be able to hear the announcement that inspired this drawing in this POV here. Yays.
>Also the music for this ride is also pretty sweet, and you can check that out here.