I think that in general, you don’t just land even those in the open sea, use sheltered waters, like a bay.

I remember that in the USS Indianapolis rescue, the seaplane that showed up wasn’t supposed to land on open ocean.

https://en.wikipedia.org/wiki/USS_Indianapolis_(CA-35)

Navy command did not know of the ship’s sinking until survivors were spotted in the open ocean three and a half days later. At 11:25 on 2 August, a PV-1 Ventura flown by Lieutenant Wilbur “Chuck” Gwinn and his copilot, Lieutenant Warren Colwell, and a crew of three other men spotted the men adrift while on a routine patrol flight.[28] Gwinn reported his findings of up to 150 men back to his base at Peleliu. He immediately dropped a life raft, other life-saving equipment and radio transmitter. All air and surface units capable of rescue operations were dispatched to the scene at once.

First to arrive was Gwinn’s commanding officer, Lieutenant Richard Atteberry. He and his PV-1 crew relieved Gwinn’s crew, ordering them to return to base because of very low fuel. Atteberry continued to circle the area and guided the arrival on scene by an amphibious PBY-5A Catalina patrol plane flown by Lieutenant Commander (USN) Robert Adrian Marks.

A Catalina is a seaplane.

Marks and his flight crew spotted the survivors and dropped life rafts; one raft was destroyed by the drop while others were too far away from the exhausted crew. Against standing orders not to land in the open ocean, Marks took a vote of his crew and decided to land the aircraft in twelve-foot (3.7 m) swells. He was able to maneuver his craft to pick up 56 survivors. Space in the plane was limited, so Marks had men lashed to the wing with parachute cord. His actions rendered the aircraft unflyable. After nightfall, the destroyer escort USS Cecil J. Doyle, the first of seven rescue ships, used its searchlight as a beacon and instilled hope in those still in the water. Cecil J. Doyle and six other ships picked up the remaining survivors. After the rescue, Marks’ plane was sunk by Cecil J. Doyle as it could not be recovered.[29]

I guess maybe the island there could be a cay and there could be a circular reef that creates a sort of underwater bay, and maybe that’s adequate to create a calmer area.

EDIT:

https://www.quora.com/Can-a-seaplane-land-in-the-ocean

Can a seaplane land in the ocean?

Generally no: Seaplanes need relatively calm water to land in. I was assigned to P5M Martin Marlin seaplanes squadron for 3 years. Not one of our squadron’s aircraft landed in the open sea. They would only do so in an emergency. The aircraft that I was a crewmember in did run low on fuel, and landed in Buckner Bay Okinawa, a relatively sheltered body of water. There was a sea/air rescue plane called a Grumman Triphibian, in a rescue situation it would land in heavy seas. [My commanding officer’s aircraft.] The role of the rescue seaplane has been replaced by the helicopter.

I guess you could argue that in both examples, seaplanes could do so in an emergency, though, and I suppose this could constitute that.

It’s only a ‘see’ plane. The kind you only see but never get rescued by.