I remember having the Dinky Sea King helicopter and Apollo capsule when I was a nipper. It was a chunky die-cast chopper.
I loved the hook oon the string which winched the pyramidal space capsule up and down.
Not sure if I ever lowered it into water, although it probably floated. Did you have a splashdown?
I just can't recall if it came with astronauts. Would a SpaceX Golden Astronaut fit inside? Alas I am without the Sea King set these days so can't check!