I would say the temps would be 23c to 24c in June and peaking in august at 26c the warmest sea in turkey is around the antalya area which peaks at 29c to 30c

These site's has present sea temps and forecasts

http://www.meteor.gov.tr/2006/english/eng-seasurfacetemp.aspx

http://www.weatheronline.co.uk/eurowas.htm

Yep you'll be fine not too much shrinkage of anything! I'm a real wuss when it comes to sea temperature but go in it in that area of Turkey from June to September, August is obviously best for me. My husband windsurfs in it all year round although he wears a lightweight wet suit from October to April.

Thank you.