I have personally watched one stay underwater for that long. Snakes are cold-blooded reptiles. They often are found on exposed rocks and pavement, sunning themselves. Some snakes have a hinged jaw that opens wide to allow them to swallow their prey. Prey is swallowed whole and digested over a week of two depending on the size of the prey.
Some snakes are venomous.
Snakes can a well developed sense that allows them to sense heat. This helps them locate prey. There are four ways that snakes move about. Each movement produces a different track. The illustration below shows the different types of snake movement.