Norway plans to build a "floating tunnel' under the sea

The video discusses a proposed highway route between Christian Sand and Trondheim, featuring bridges and submerged floating tunnels. These tunnels, installed 30 meters underwater, aim to halve travel time. They will be anchored to the seabed or pontoons for stability, functioning like regular tunnels for vehicle passage.

What is the purpose of the pontoons in the floating tunnel system?

Describe how the floating tunnels will function once installed.