The two men halted at the edge of the canal, hiked their tunics, then fumbled with their loincloths. Soon two arcs were gurgling across the filmy surface. “Hmm,” Xinemus said. “The water’s warm.” Even terrified, Esmenet rolled her eyes, smiled. “And deep,” the Prince replied. Xinemus cackled in a manner at once wicked and endearing. After securing himself, he slapped the other man on the back. “I’m going to use that,” he said merrily, “the next time I piss back here with Akka. If I know him, he’ll damn near fall in.” “You’ll have a rope to throw him at least,” the taller man replied. More laughter, at once hale and warm.
--- The Darkness That Comes Before by R. Scott Bakker
The water's warm is probably referring to the warm sensation of pee but how does it relate to And deep?