You are talking about surface tension. The importance parameter is speed not height and “like concrete” is a drastic simplification as both behave very differently on impact.
Notably whereas high divers have reached speeds of 60 mph the Artemis II splashed down at around 1/4 that speed a speed you too can obtain by jumping from about 10 feet up.
Water is as hard as concrete from a large height.
They splash down in water because there is less chance of hitting something.
Due to its low density and viscosity, water cushions the spacecraft enough that there is no need for a braking rocket to slow the final descent
https://en.wikipedia.org/wiki/Splashdown
They have parachutes to slow decent, so its not just a hard drop from space to ocean surfacw
You are talking about surface tension. The importance parameter is speed not height and “like concrete” is a drastic simplification as both behave very differently on impact.
Notably whereas high divers have reached speeds of 60 mph the Artemis II splashed down at around 1/4 that speed a speed you too can obtain by jumping from about 10 feet up.