Which type of mine is designed to detonate when a vessel passes over it?

The type of mine designed to detonate when a vessel passes over it is classified as a bottom mine. Bottom mines are specifically anchored to the seabed and are triggered by the pressure exerted when a ship moves over them. This mechanism allows them to effectively engage targets that are traveling on or near the water's surface.

In contrast, drifting mines are capable of moving with currents and are triggered by vessels coming into proximity, rather than directly above. Floating mines, although they remain on the surface of the water, tend to be utilized against vessels that come close to them, relying on different activation methods. Shallow mines are typically employed in coastal regions where vessels navigate at lower depths. Thus, each of these other types operates under different principles and conditions than that of a bottom mine, making the bottom mine the correct answer in this context.