The victim, believed to be in her forties, was taking a stroll next to the water around 9am on Monday, December 31, when she noticed a white man, aged between 50 and 60-years-old, further down the path. He then exposed himself to the woman.
The offender was wearing a dark jacket, grey jogging bottoms and trainers, as well as a a grey chequered beret-style hat that had a peak to the front.
PC Mark Ginn from Bracknell police station said: "I would like to hear from anyone who may have noticed a man fitting the above description in the area."
If you can help, please contact PC Ginn via the Thames Valley Police Enquiry Centre on 101 or, to remain anonymous, call Crimestoppers on 0800 555 111.