A cold plunge is a form of hydrotherapy that involves immersing oneself in very cold water for a brief period of time, usually less than 5 minutes. It is used as a way to reduce inflammation, boost circulation, and increase energy levels. Cold plunges can be taken in a natural body of water, such as a lake or river, or in a specially designed cold plunge pool or tub. Many people find that the shock of the cold water can be invigorating and even meditative, and it is a popular practice among athletes and health seekers. It is important to take proper precautions and gradually acclimate oneself to cold water immersion to avoid potential health risks. Always remember to breathe.

Brief cold plunges of a few minutes can provide benefits such as reducing inflammation and improving circulation; however, longer cold immersions can have other benefits as well. One of the main benefits of longer cold immersions is the activation of the body's regulatory mechanism, such as the release of endorphins and increased circulation to the organs. This process will promote faster recovery from injuries, reduce muscle soreness, and improve overall physical and mental well-being.

Longer cold immersions have also been shown to improve the immune system by increasing the production of white blood cells and other immune cells and has been shown to be a strong component of a larger weight loss program. Additionally, cold immersions can help to reduce stress and anxiety by activating the body's natural relaxation response.

Cold plunge and contrast therapy are two related but distinct practices used in hydrotherapy.

The alternating hot and cold water immersion in contrast therapy provide a greater range of biophysical responses and therapeutic benefits than cold water immersion alone. The hot water immersion can help to improve circulation and relax the muscles, while the cold water immersion can help to reduce inflammation and stimulate the immune system. Together both will aid in lymphatic circulation, tissue oxygenation, and general circulation and is beneficial for overall physical health and mental well-being. Both cold plunges and contrast therapy have been studied for their potential health benefits, but there is more research available on the benefits of contrast therapy.