Wing-in-Ground Effect (WIG) is an aerodynamic phenomenon that occurs when a wing or a set of wings are positioned close to the surface of the ground or water, causing an increase in lift and a reduction in drag. When an aircraft or a watercraft moves through the air or water with its wings in the WIG, it experiences reduced fuel consumption and increased efficiency compared to flying at higher altitudes or sailing on the water's surface.

The concept of WIG has been studied and tested for many years, and has been used to develop a range of aircraft and watercraft designs, including the Caspian Sea Monster, also known as the Ekranoplan, a Soviet-era ground effect vehicle that was capable of traveling at high speeds while flying just above the surface of the water.

WIG vehicles have a unique design that includes long, narrow wings and a short, sturdy body that allows them to take advantage of the ground effect. They are used for a variety of purposes, including military operations, search and rescue missions, and commercial transportation. However, WIG vehicles have some limitations, including their restricted operational altitude, which can make them vulnerable to rough seas and other hazards. As a result, the use of WIG vehicles remains somewhat limited and specialized, but continues to be an area of interest for researchers and engineers seeking to develop innovative new transportation technologies.