A glass bottom boat is a boat with sections of glass, or other suitable transparent material, below the waterline allowing passengers to observe the underwater environment from within the boat. The view through the glass bottom is better than simply looking into the water from above because one does not have to look through optically erratic surface disturbances.

The effect is similar to that achieved by a diving mask, while the passengers are able to stay dry, out of the water. It is an ideal adventure for non-swimmers to enjoy and lively spot the tropical fish and marine life without getting wet.