Hello everyone! I can't clearly understand a sentence. Could you help me?
What does "thick churn" mean here?
Thank you in advance.
Source The Legend of America's Most Dedicated, Most Creative People Smuggler
Elden kept his ears tuned to the waves breaking on his left. If the sound grew too loud, he was drifting too close to shore; if it began to fade, they were heading farther out to sea. It would be five hours before they would come ashore at Imperial Beach in California. Until then, they were alone with the thick churn of the ocean, the velvety depths, the dark and the rain curtaining them off.
What does "thick churn" mean here?
Thank you in advance.
Source The Legend of America's Most Dedicated, Most Creative People Smuggler
