According to Wikipedia:

Native Americans spent the summers fishing from the island’s shores, and named the island Wa-na-ka-wagh-kin, which has been translated as meaning “good land”. Artifacts excavated on Iona Island are on display at the Bear Mountain Trailside Museum and Zoo. In 1683, members of the Van Cortlandt family purchased the land from the natives. It was originally known as Salisbury Island, and later as Weyant’s Island (for the local Weyant or Weiant family). The island has also been known as Beveridge’s Island. It was occupied by British troops during the American Revolution.

In 1847, it was bought by John Beveridge for Dr. E. W. Grant, his son-in-law, who renamed it Iona Island and planted it with Iona grapes and fruit trees. Grant supplied the Union army with produce during the Civil War. In 1868, his creditors foreclosed on the island.

The island was purchased by a group of investors, and a summer resort was developed on the island. Grant’s mansion home became a hotel, and the investors gradually added an amusement park with a carousel, Ferris wheel, dance floor, pavilion, and picnic grounds. It also had a dock to accommodate steamboats which brought pleasure-seekers up from New York City and New Jersey. The construction of the West Shore Railroad across the island in 1882 made it even more accessible to tourists.

In 1899, the island was bought by the U.S. Navy for use as a naval ammunition depot, becoming one of the largest ammunition facilities in the nation, at that time. On November 4, 1903 an explosion at the site killed six workers, and blew out windows across the river in Peekskill, three miles away. The explosion occurred while men were drawing the explosive charges from a consignment of old shells recently arrived from the battleship Massachusetts.

The depot supplied much of the munitions for both World War I and II, and remained in service until 1947. Approximately five of the original 164 arsenal buildings remain, which the park now uses for storage. Following World War II until the early 70s, the famous “mothball fleet” of decommissioned warships were moored near the island at Tomkins Cove.

The island was bought by the Palisades Interstate Park Commission in 1965. In 1974 it was named a National Natural Landmark by the National Park Service. As an active wildlife sanctuary, Iona Island is currently closed to the public, however the island and its wildlife may be viewed from overlooks on nearby Route 6, as well as from overlooks within Bear Mountain State Park. Although public canoeing and kayaking is prohibited in the marsh itself, free guided canoeing programs to the marsh are offered during the summer. However, the waterway around the marsh are affected by tides and hence are “navigable-in-law” by the public.

Taken with a Sony RX-100 M3.