Fresh water lake, knee to chest deep for 1-2 km. Flat water with very small waves now and then (about 50 cm). Shells on the bottom. Better to wear shoes as protection.
Air: May-August about 15-30°C, Sept-April: 0-15°C. Water: May-August fine (a shorty will do), from Sept-April you need a wetsuit, in Dec/Jan it can get cold (around zero degrees Celcius). Jan-Aug unpredictable, can be anything. Sept-Dec usually cloudy/rainy weather though in this period, especially when there's wind.
Jan-Aug unpredictable, can be anything. Sept-Dec wind nearly every day, and usually some pretty good weeks. Usually cloudy/rainy weather though in this period, especially when there's wind. Best directions W, SW, S and SE.
From Amsterdam take the car or train to Hoorn, from there you'll need a car (you can rent one in Hoorn), from Hoorn it's about 10-15 min. drive. Follow the signs HN80, as soon as you've taken the right to the Industy Plan HN80, take a right again, follow the road until the dike, take a left. Follow the road and you'll see the kites in about 2 minutes. There's kiters there everyday, no matter temperatures. Free parking.