depth indicator

例句：

1. 1. The depth indicator is used to measure the depth of water.
   深度指示器用于测量水的深度。
2. 2. The depth indicator is crucial for navigation in deep waters.
   深度指示器在深水中导航至关重要。
3. 3. The depth indicator can be used to detect changes in water temperature.
   深度指示器可以用来检测水温的变化。