Question

A dolphin is at the surface of the ocean. What is the dolphin’s elevation?

The dolphin dives 20 feet below the surface of the ocean. What is its new elevation?

Answer 1

It's elevation at the surface is 0, and the elevation twenty feet below is -20.

Explanation:

The surface level is 0, and diving 20 feet under means 0 - 20, which is negative 20, or -20.