It was a leap of faith.

Saoirse Kennedy Hill’s father paid tribute to his daughter, who died last week of a suspected drug overdose at age 22, by overcoming his fears and jumping from a Hyannis Port buoy.

“Saoirse’s Dad, Paul Hill, has a terror of both heights and water,” wrote Robert F. Kennedy Jr. in an emotional Instagram post Wednesday documenting the loving memorial in honor of his niece.

“Having grown up in the catholic ghetto of the Falls Road in Belfast, and spent most of his adult life in 38 British prisons, he never learned to swim. Nevertheless, he wanted to jump off the HH buoy in Saoirse’s honor.”

The photo shows the Irish-born Hill — one of the Guildford Four, a group of men wrongfully convicted and imprisoned in the 1974 bombings of two English pubs by the Irish Republican Army — airborne with the red-and-white buoy behind him, arms aloft and long hair flowing in the Massachusetts breeze as he plunges toward the water.

“He asked us to be there to rescue him when he hit the water,” the caption continues.

A second snap — captioned “Baptized” — shows the moment of impact, as Hill’s legs cut through the chop.

And a third, captioned “Rescue,” shows a drenched Hill, 65, with one arm raised in a triumphant fist pump, as his other is hooked around an orange life preserver.

The post also links to RFK Jr.’s heartfelt eulogy to Saoirse, who was found in cardiac arrest at the Kennedy compound on Cape Cod on Aug. 1 and laid to rest Monday.

The official cause of death is pending a toxicology report.

“She put out a bright light. Everybody loved her. She made people feel good,” RFK Jr. wrote.

“Anyone who is tempted to feel badly that you didn’t do enough for Seersh, put that thought away. She felt loved by everyone in this church. It was all authentic.

“She was very, very, very easy to love.”