The Answer:
Snakes are some of the most unique creatures on the planet. They have no limbs, only move through strong abdominal muscles, and some can hardly see, but simultaneously are some of the deadliest predators on the planet. They hunt with camouflage, guile, and precision. They sneak through underbrush, climb up trees, and dig in the ground. They can poison, strangle, and literally swallow their prey.
While obviously they cannot fly, perhaps the only thing that could make then more dangerous was if they had the ability to swim. Well guess what, snakes can swim! Let that become your nightmare fuel. All species of snakes can swim. In fact, most animal species are born with the ability to swim. That being said, snake species do have preference towards either water or land. Most will spend their entire lives on land, while some live near exclusively in the water.
How do snakes move? Without limbs it serves to be a rather difficult process. So far, five methods of locomotion have been identified. The first is called lateral undulation. This method is by far the most common method of movement. Essentially, the wind themselves from side to side, using their strong abdominal muscles (pretty much the only muscles they have) to pull themselves forward. This movement method starts at the head. They swing it to one side first, then the other. These undulations continue down the body. It is like the snake is drawing a big ‘S’ with their body.
Snakes also use this method, or at least something nearly identical, to swim. Lateral undulation also allows snakes to move across smooth surfaces, where the lesser amount of friction between the and the ground is not as ideal for movement. While in water, snakes use lateral undulation in conjunction with the surface tension of the water to stay afloat. Each time they draw the ‘S’ with their body, the movement, especially of the head, applies force to the water behind them. One of the basic physical laws of our world is that every action has an equal and opposite reaction. Thus, when force is applied behind the snake on the water, it will be propelled forward by the equal and opposite force from the water. The tail especially provides a lot of forward velocity due to the built up momentum from the rest of the body moving.
Snakes are very adept at moving smoothly and gracefully on land. But most snakes find a little more difficulty in moving with precision and speed on the water. But snake species that live in the water are experts at swimming underwater and gliding along on the surface. Water snakes have a flattened structure that helps them in their movement, allowing them to knife through the water with much more efficiency than their land inclined cousins. Some species even have paddle-like tails, helping propel them forward even more quickly.
Some water-based species are better swimmers than others. A few snake species can travel for miles without stopping. Many differences in swimming styles also exist. For example, the venomous cottonmouth snakes, which live the coastal plains of southern America, often hold their head just above the water while they swim. This method is not the most efficient in terms of speeds, but it does allow them to keep an eye out for predators.
So much information about snakes can be useful. There are ways to distinguish between venomous and harmless snakes.