After entering that body of water, Minos only had to manipulate a little of his respiratory organs to become fully accustomed to the underwater world.
Small membranes appeared at the sides of the base of his neck, and inside his nose, a membrane appeared to protect his lungs from water ingress.
He breathed underwater in a few seconds through these simple changes, swimming after that beast.
First, they went down for several meters in that area, which was somewhat narrow. But soon, they reached the bottom of that body of water, where there was a wider space below the rocks that held the surface ground.
Minos saw the great beast showing him the way through that place that was not at all dark due to underwater plant roots that shone like stars.
Because of these organisms, Minos could see tens of kilometers away from him in this grand underwater place where people on the surface would not imagine how much space there was there.