Aquaman (DC Comics)
No one can rule the seven seas but with the right scuba gear people can swim under water for long periods of time. There are deep sea divers who have pushed themselves to new human limits.
Wolverine (Marvel Comics)
Researchers at the Max Planck Institute of Microstructure Physics in Halle, Germany, have developed the atomic layer deposition process that be used to strengthen bones like Wolverines. Youtuber Colin Furze has already made external claws.