The **seat belt** is the passive safety system that prevents the submarining effect in the event of an accident. This effect occurs when the body slides downward, under the belt, due to improper placement of the belt or an incorrect seat position. To prevent it, it is crucial to fasten the belt properly and ensure it is correctly adjusted to the body. Additionally, it is important not to recline the seat too far back and to avoid placing objects like towels or cushions that could cause the seat to slip.

The seat belt protects vehicle occupants in the event of a sudden impact or rollover, keeping them in their seats and preventing them from being ejected. Wearing it properly significantly increases the chances of surviving an accident. Therefore, the seat belt is essential for preventing the submarining effect and protecting passengers in emergency situations.