4 sentences

1. 这种相机可以进行水下拍摄。

   zhè zhǒng xiàng​jī kě​yǐ jìn​xíng shuǐ​xià pāi​shè.

   This camera can take photos underwater.

   Source: Dong Chinese Dictionary

2. 你想让我去跟整个水下文明开战？

   nǐ xiǎng ràng wǒ qù gēn zhěng​gè shuǐ​xià wén​míng kāi​zhàn?

   You want me to go to war against an entire underwater civilization?

   Source: OpenSubtitles

3. 潜艇的推进器在水下发出的噪音很小。

   qián​tǐng de tuī​jìn​qì zài shuǐ​xià fā​chū de zào​yīn hěn xiǎo.

   The submarine's thrusters make very little noise underwater.

   Source: Dong Chinese Dictionary

4. 湖水水位下降以后，原本淹没在水下的石头露出了水面。

   hú​shuǐ shuǐ​wèi xià​jiàng yǐ​hòu, yuán​běn yān​mò zài shuǐ​xià de shí​tou lù​chū le shuǐ​miàn.

   After the lake's water level dropped, the stones that were originally submerged were revealed above the surface.

   Source: Dong Chinese Dictionary