The water is high in sediment, visibility 10cm, pollution is there but acceptable. Never got really sick despite swallowing a lot. At high tide you have a 5 square km playground with chest deep water, at low tide you have to walk out a 1km or so, but then you find a channel with perfectly flat water. Generally you have quite a swell, some half to one meter waves. No surfing at all, kind of choppy also since the water is not really flat. Little waves with East winds.
Ugly promenade, enforced with a lot of concrete, kind of scary, some awful boulders protecting the 3m concrete wall, leg breaker we call them. Easy launch and land in low tide, a bit tricky in high tide.
The water is above 20°C from May to October, reaching 30°C in August. A wetsuit is recommended due to the pollution and the numerous sticks in the water. Off-season is ok.
Southerlies are prevailing in summer. Usually best wind in the area, wind machines are there, in summer almost everyday, still Shanghai is a light wind region. In summer Southeast, in winter Northwest. Best is East, then there are little waves, and sideshore. Offshore is dangerous, no one would bother if you drift away, they would watch you drift out of sight and go home.
Follow the outer ring South from Hong Qiao airport, enter the A4 South, follow the signs for Fengpu bridge, cross Fengpu bridge exit number 11 from freeway, then continue South until you hit the Hangzhou Bay, can't miss it.
2RMB entry fee (equals 0,25 US cent). Still be nice to all the people there and don't offend the other mud plain users. The police could close us out without reasoning. This is China.