It really depends upon what you are looking for.

Capriccio Di Mare has already been mentioned and it's one of my favourites for Italian food and particularly the pizza.

For places all within walking distance of the ferry dock, try Bamboushay Lounge (local food such as roti and North American cuisine), Origin (Japanese - very nice), Pusser's (North American pub type food), The Watering Hole (Friday night is pizza night) and just a short cab ride away is Sharky's for Mexican food and pizza as well. They are all listed here and each is pretty casual, so you don't have to worry about what you look like.

There's also The Dove (French cuisine) which has just re-opened and a new place called Fantasia By Georgio (Italian food). Both of these places are a little fancy and unless you go shower and fix yourselves up, may not be appropriate for you if coming straight off the ferry.