Translations for ocean in French

Here are paragraphs from public domain books translated:

"A dabbler in science, Mr. Holmes, a picker up of shells on the shores of the great unknown ocean. I presume that it is Mr. Sherlock Holmes whom I am addressing and not——"	— Oh ! un simple minus habens , un ramasseur de coquilles sur le rivage du grand océan inconnu de la science. C’est à M. Sherlock Holmes que je parle ?….
The Hound of the Baskervilles, by Arthur Conan Doyle	Le Chien des Baskerville, de Arthur Conan Doyle