To determine the new position of the submarine after it descends 108 feet from its original depth, you can add the descent to the current depth. The submarine starts at 550 feet below sea level, which can be expressed as -550 feet.
When it descends 108 feet, you would calculate it as follows:
\[ -550 - 108 = -658 \text{ feet} \]
So, the new position of the submarine is 658 feet below sea level.