A jogger was left " very shaken" after a man indecently exposed himself to her in Walton.
The victim, a woman in her 30s, was jogging on the riverside towpath in the direction of the leisure centre near to the Weir Hotel pub on Wednesday, April 5 at around 6.35pm when the sexual offence happened.
The man is described as white, around 30 years old and of a medium build. He was wearing black sunglasses, a dark green hooded top with the hood up, dark coloured trousers and carrying a rucksack.
Detective Sergeant Alex Maguire, said, "Although thankfully unharmed, the victim was understandably very shaken by the ordeal.
"This incident occurred in a busy location so other joggers, dog walkers or river users may well have seen something happening.
"I would urge anyone who may recognise the description of the man who or who may have seen anyone acting suspiciously in the area at the time of the offence to contact Surrey Police – any information, however small it may seem, could prove vital to the investigation.
"Similarly, I would urge any victims who have experienced an indecent exposure to get in touch. This type of offence is totally unacceptable and incidents of this nature are taken extremely seriously."
Anyone with information is asked to call Surrey Police on 101 quoting reference 45170035078 or use the online reporting system found at the website.
Alternatively the independent charity Crimestoppers can be contacted anonymously on 0800 555 111.