Since the dawn of humanity, man has longed to conquer the ocean, which is why the invention of the boat was followed swiftly by the adoption of the high-five. Celebrate man's triumphs with today's Groupon: for $135, you get a two-hour boat rental for up to 10 from SJ Koch Electric Boats, departing from Annapolis or Baltimore Inner Harbor (a $275 value).

SJ Koch Electric Boats' rides transform land-bound congregations into aquatic revelries with electric-powered, canvas-enclosed, heated Duffy boats. Before skipping across the waves, drivers and their crews take in a 30- to 45-minute operating class, learning how to safely run their floating vehicle and effectively dodge schools of sea monkeys. Rental times begin upon the lesson's conclusion, and parties set off armed with a map charting the course and points of interest along their chosen body of water. Trips departing from Annapolis may take in a tour of the Naval Academy and historic structures such as the Maryland State House, and the Baltimore Inner Harbor boasts Fort McHenry and a bevy of waterfront restaurants.

Navigating with golf-cart-like simplicity, Duffy boats scoot along at 7 mph on electric engines, churning out no noise or noxious emissions. Life jackets for the entire entourage can be found onboard, although infant vests and sailor bellbottoms should be requested prior to the journey. Passengers crank up the onboard radio or personal iPods through the vessel's four-speaker audio system, and fuel up on personal snacks and libations stored in the built-in coolers. Most boats have bathroom facilities, catering to guests' comfort and goldfish burials at sea.