The Spacewalk was one of many attractions in the Nuka-World Amusement Park in 2077, before the Great War. As the name implies, it was a spacewalk simulator.
The Spacewalk is a tunnel leading from the upper stands of Starport Nuka down towards the RobCo Battlezone. Laser turrets are mounted on the ceiling and floor of the tunnel. The main goal with this attraction is to reach the top of the tunnel located in the upper stands of Starport Nuka.
A Star core can be found at the bottom of the tunnel.