How deep are the waters around Mumbai?

Does anyone know, or have any sources of information, links, that kind of thing, about the depth of the waters around Mumbai?

I am specifically wondering about the depth between Apollo Bunder and Alibag... and also the depth from Marine Drive outwards.

This intriguiging curiousity is sparked by the recent tragedy involving the ferry between Alibag and Apollo Bunder and was asked to me by my teenage nephew.

Any links would be especially helpful. Thanks.