If you're cruising in your boat at dusk, you should encounter hundreds of bats along the way. I certainly do and it's the only time I really enjoy them. Hate when they get in the camp!!!!
As an aside, I sat at the entrance of a cave in Northern Australia at dusk and watched tens of thousands of bats emerge from the entrance. Brown snakes hung from the trees just outside the entrance and gobbled some of them up as they flew out. And those were the smallies. Their big bats - flying foxes or fruit bats - are about the size of eagles and it's pretty amazing (read: creepy) to see a bunch of those circling overhead.
