There is no way to count the mass due to the overwhelming size of the Pacific Ocean, migration patterns of animals, and vast amount of unexplored underwater terrain. We know less about the ocean...
There are 70 million cubic miles of water in the Pacific, which equates to 187,189,915,062,857,142,857 gallons, (187 quintillion gallons or 187,189,915,062 billion gallons), of water in the Pacific...