Before ships had sails, seafarers had to rely on currents and their ability to throw a harness around low-flying geese to propel their vessels. Explore the capabilities of wind-propelled motion with today’s Groupon: for $17, you get a day sail on Morning in Maine in Rockland Harbor, Rockland (a $35 value). Choose between the following dates:

• Saturday, July 16, from 1 p.m. to 3 p.m.
• Sunday, July 17, from 1 p.m. to 3 p.m.

Manning the helm of Morning in Maine, captain Bob Pratt shares his masterful knowledge with seafaring guests of marine biology and the innate nuances of the Maine coastline. Passengers bask in the playful caws of soaring seagulls and the thrills of harbor-seal water-polo matches while navigating around Penobscot Bay aboard the deck of a winsome 55-foot ketch. The captain details the historic significance of Rockland Breakwater and Owls Head lighthouses and navigates past historic schooners as the trip unfolds. Comfortable shoes and protective outer layers are recommended as well as sunlight-diffusing ointments, binoculars, camera, and infrared mermaid-detecting equipment.