It is the broad with the largest surface area, and the water is slightly brackish, due to its proximity to the sea.[9] The navigation channel is only 1.5 m deep, with much of the broad being shallower; it is 1.4 km2, making it one of the largest expanses of open water in East Anglia.
Hickling Broad was used as reserve station for sea planes by the RNAS, in the period 1916–1918, as an escape for RNAS South Denes. It was known as RNAS Hickling Broads. Contractors started building a concrete slipway, but this was never completed. Eventually, Hickling was only used for two emergency landings. A separate arrangement allowed seaplanes destined for Great Yarmouth to land on the calmer waters of the broad if the sea were too rough (this arrangement stands to this day). RNAS South Denes was located in the area which is now the South Denes Camping and Caravan site.[11] There is a commemorative Blue plaque in Regent Street in Great Yarmouth, it reads "Headquarters of the Royal Naval Air Service Occupied these premises during WWI April 1913-November 1918 Flying land & sea planes from South Denes, Hickling Broads, and heavily involved in anti Zeppelin warfare."[12]