You can usually contact your local CVB (Convention Visitors Bureau) and see if
they can help you. Most of these organizations usually publish tourist guides
on where and what to do. Advertising within the hotels is another possibilty.
Most hotels supply their guests with coupon or guide books to local
attractions. You could contact them about having your bar including in these
guide books.
You can always try a cross-promotion with a popular day-time attraction such
as a group that gives local tours or maybe something like a waverunner rental
company. You could do something as simple as swapping onsite advertisements
or do promotions to where you give away a free tour as a door prize and maybe
they give out free drink coupons for your establishment.
Good Luck!