What is a word that starts with bath and mean deep. Please use the word you have and put it in a sentence. Thank you!?

"Bathometer" is a device for measuring the depth of water. A bathometer is used to measure water depth without the use of a sounding line. The bathometer does not require a line to extend to the bottom because it measures the difference in the gravitational effect of the water surface and of solid ground. Whatever depth measured by a bathometer is adjectivally called "bathometric."

Example:

The bathometric depth of the lowest discovered point in the underwater cave determined it to be 712 feet below the lake's surface.

The bottom of the cave was measured to be a bathometric 712 feet, because its lowest point isn't directly below the surface of the lake.