863.50 cubic inches is about 0.00000000003 times as big as Sydney Harbour
In other words, it's 0.00000000002520 times the size of Sydney Harbour, and the size of Sydney Harbour is 39,700,000,000 times that amount.
(formally Port Jackson, a.k.a. Sydney Harbor) (Sydney, New South Wales, Australia) (total estuary water volume at high tide) Lending the term "sydharb" or "sydarb" to comparable quantities of water, Sydney Harbor contains approximately 34,300,000,000,000 cubic inches of water. Snapper Island, a onetime naval facility loocated in the Harbour, was transformed by the dredging efforts of the Australian Navy from a 2,360 sq. m (25,400 sq. ft) outcropping to a 16,500 sq. m (178,000 sq. ft) island shaped roughly in the outline of a boat.