Dr.Wujastyk,
Yes, 'Ocean' has often been used in Ancient Indian texts. The probable reason may be to relate the vastness of our life ,with its myriad of complexities. to the vastness of an ocean. This perhaps is relevant, since the ultimate aim of our life,according to our ancient Indian philosophy ,is to attain enlightenment in life,and thereby bypass all mundane problems ,by way of Realisation of our Self ( i.e.Atmana) .

A quote from Shankaracharya's Vivekchuramani-

Uddharen Atmanam Atmana Magnau Samsar Baridah .

Here the word'Samsar Baridah'implies THIS LIFE-OCEAN depicting the various shades, Crest-nadir,the tumultous multititude of our life-cycle


ALAKENDU DAS