For the first time in a century, the public on Saturday will be welcome to explore a part of Clapboard Island in Casco Bay that will soon be permanently open to the public.

The Maine Coast Heritage Trust, which is purchasing 15 acres of the island later this summer, is offering the one-day preview of the land before it completes the acquisition in August for $1.6 million, $200,000 of which was contributed by the town of Falmouth.

The group has successfully raised $1.4 million so far, and expects to close on the deal Aug. 15.

A portion of the money, $200,000, will be saved as a conservation endowment to keep the island well maintained for future visitors. With only about $200,000 left to raise, the Maine Coast Heritage Trust is ready to show the public what the island has to offer, said Susan Gilpin, president of the Friends of Clapboard Island, a group that aided the fundraising effort.

The nonprofit land conservancy will offer free boat rides between the Falmouth Town Landing and the island between 8 a.m. and noon, the duration of the preview.

Boaters, kayakers and anyone else with a seaworthy vessel may make the short journey on their own, Gilpin said.

At roughly 40 acres, the spit of land has been in private hands for decades. It features a large vacation home in the southern portion, and a small cottage that stands on the land being purchased by the conservancy.

The 3,100-square-foot cottage has five bedrooms and sits on two acres, and the conservancy group is offering it for sale for about $769,000, according to a real estate listing. Proceeds will help the group pay for the land around it.

The part of the island that is not part of the conservation deal has an estate-sized, eight-bedroom home on about 22 acres, and is for sale for nearly $6 million.

A walking path about a mile long leads around the island’s perimeter, and will give visitors access to watch wildlife or enjoy a picnic, Gilpin said. For bird watchers, two bald eagles and three ospreys call Clapboard their home.