Depends what reef you go to from tvl, my missus took her old man to Kelso reef last year and they went snorkelling.
There's a few creeks you can go swimming up north (crystal creek and paluma) there's a good little pub at Rollingstone on the way up. The locals there are decent to chat to. The difference between Cairns an Tvl is that Cairns is a bit closer to the reef than and it gets more rainfall so it has always lended itself more to the tourists, whereas Tvl is more blue collar/defence/uni students. The nightlife here is alright but there is a bit of violence on the club strip as the army boys like to blue a bit and if they've been out bush for a few weeks then it doesn't take much for them to get pissed.
Either way you can get decent food, piss and watch some footy up here. Throw in some boobs and really there's not much more man could want.............