For something original to do in the tropics I would highly recommend Prawn Star in the Harbour at Cairns. There is nothing quite like sitting on a boat drinking a beer eating extremely fresh seafood as the sun sets over the water, it is quite frankly breathtaking. Although the menu is sparse, what they do they do extremely well. You get to choose from prawns, crabs, bugs, oysters and salmon or a platter combining the lot all served with the pre requisite seafood sauce and lemon. To top it off they have some of the cheapest beer prices going around with a beer only setting you back $5. The best times to go are early or late as they don't take bookings and there isn't a great amount of seating, however if you are unlucky enough not to find a seat you can always take away and each on the water front however the real experience is to be found eating on the boat. There is a reason why this is so highly rated by everyone who visits because it is honestly just a great experience!