The Kala Pani (lit. black water) represents the proscription of the over reaching seas in Hinduism.[1] According to this prohibition, crossing the seas to foreign lands causes the loss of one's social respectability, as well as the putrefaction of one’s cultural character and posterity.[2] Nowadays this practice is not followed by most Hindus who see it as backwards.

https://en.wikipedia.org/wiki/Kala_pani_(taboo)