In this research paper the underwater welding and cutting processes will be analyzed in detail. Various platforms, pipelines, dams, bridges, power stations etc. require maintenance by using the underwater technology. Such processes often result in environmental contamination due to improper handling of such technology, and therefore, a high level of expertise in this area is required from people who are responsible for carrying it out. Construction and maintenance of the aforementioned structures require professional underwater (wet or dry) welding techniques. When it comes to choosing the specific technique for underwater welding, the primacy is given to dry underwater welding. It provides high effectiveness and flexibility, which implies mobility and quick work performance that is needed. This furthermore implies that the cost of doing the work itself is much lower, too. Underwater welding participants are often exposed to high risk and, therefore, the use of professional equipment is highly required. Such processes often result in damage and cracks. Because of this, combined underwater welding uses underwater testing and control. Magnetic particle testing, ultrasonic testing and visual control are most commonly used. This will allow quick response if a repair or renovation is needed. Dry underwater welding is more commonly used for platform operation and can be carried out in four different techniques: local dry underwater welding, welding in dry welding mines, welding in dry hyperbaric chamber and atmospheric underwater welding. For wet underwater welding there are three basic techniques: swing technique, retraction technique and backward technique. All of these listed techniques will be further described in this paper.