Bombay is a peninsula, so is surrounded on three sides by water. I checked out the beach near Marine Drive, a posh bit of town near the tip of the city, this weekend. The beach is pretty nice, but I wouldn't go swimming in it. The sewage of the city pumps directly onto the beach. That doesn't seem to discourage everyone though.
Beach Near Marine Drive (1 of 2)
Beach Near Marine Drive (2 of 2)
I also saw a political rally in town, near the Taj hotel. The kid at the front was very enthusiasticaly waving the flag.