At its shortest length, the telescopic mount can be used in water 2.5 ft or less if you drive the spike 11" in the ground. This will give you 3.75" of space between the bottom of the cup holders drain hole and the water.

When fully extended, the telescopic mount can be used in water 4 ft or less if you drive the spike 11" in the ground. This will give you 1.5" of space between the bottom of the cup holders drain hole and the water.