I'm told that the nets don't touch the ground so a cheeky shark might get our ankles after all. The text below is from Wikipedia. Do they really send frogmen down twice a week to inspect the nets?
In Hong Kong, after the shark-attack death of three swimmers over 10 days in 1995, the government installed shark nets on all 32 gazetted beaches. Unlike the long-line and gill-net designs common in Australia and South Africa, these are permanent installations and are barrier nets. There have been zero fatalities since installation in 1995.
The Hong Kong nets are generally 35 mm square on the surface 2 m and 100 mm square thereafter. They are suspended off 225 mm HDPE pipe or BL14 Marine Float Lines, and anchored strongly to resist the many typhoons and waves up to 10 m. They are anti-fouled, and spend an average of 9 months a year in the water. An average net enclosure would be 500 m long and either semi-circular or rectangular in shape. They are diver-inspected a minimum of two times a week, and independent verification is required. They also exclude floating refuse, and clearly define the swimming area. They can be clearly picked out on Google Earth - at 22^14'38" North, 114^11'26" East, see "Repulse Bay".