This is the 14087th most frequent Russian word.
океанских
"Of the oceans" or "oceanic."
Here, 'океанских' (oceanic) is used as an adjective to describe 'круизных лайнерах' (cruise liners), indicating their relation to the ocean.
Я мечтаю о путешествии на океанских круизных лайнерах.
I dream of traveling on ocean cruise liners.
In this sentence, 'океанских' (oceanic) modifies 'глубинах' (depths), denoting the depths associated with or found in the ocean.
В океанских глубинах скрываются удивительные существа.
Amazing creatures hide in the ocean depths.
Here, 'океанских' (oceanic) is used to qualify 'течений' (currents), referring to the currents of the ocean.