Type the correct answer in the box. Use numerals instead of words. If necessary, use / for the fraction bar. A team of deep-sea explorers is combing ocean waters in a submarine. The submarine is at an elevation of $-355 \frac{2}{7}$ feet. The explorers spot a humpback whale and dive downward an additional $92 \frac{4}{7}$ feet. The new elevation of the submarine is feet.

Step 1 ：The submarine is initially at an elevation of \(-355 \frac{2}{7}\) feet. It then dives downward an additional \(-92 \frac{4}{7}\) feet.

Step 2 ：To find the new elevation, we need to add these two values. Since both values are negative (representing depths below sea level), the result will be a larger negative number.

Step 3 ：\(-355 \frac{2}{7} + -92 \frac{4}{7} = -447 \frac{6}{7}\)

Step 4 ：Final Answer: The new elevation of the submarine is \(\boxed{-447 \frac{6}{7}}\) feet.