Boston teems with camera-worthy sights: the USS Constitution, Bunker Hill Monument, Old North Church and of course, the entirety of the city's iconic skyline. One of the best ways to sees these and other landmarks lies out on the water. Luckily, it doesn't take a drop of fossil fuel or condensed unicorn tears to get there. Boston Green Cruises lives up to the middle part of its name with its low-emission vessels, Beachcat, Unplugged, and Water's Edge. The boats' low-emission motors hums softly as the boats accommodate from 6 to 40 passengers per tour. Aboard these vessels, Boston Green Cruises' captains charter private voyages and lead public tours of Boston Harbor and the Charles River.