1. 形容海浪很大 2. 形容人心情复杂（这么用虽然不准确，但是还是在开玩笑的时候用） 3. 形容美女非常丰满（比较低俗的网络用语）

It also means big boobs in a kidding way. 波 can mean boob in modern Chinese, like you can call a girl with big boobs 大波妹/波妹. 汹涌 is initially used to describe huge waves, well, in here you get the idea.

thank you 王肥

A few examples: (1) 勇敢的海燕在波涛汹涌的大海上飞翔。 (2) 轮船在波涛汹涌的大海上破浪前进。 (3) 轮船在波涛汹涌的海上缓慢地前进。