Officers began an investigation after a member of the public reported seeing the body in Loch Morlich, between Aviemore and the Cairngorms ski slopes, yesterday morning. The woman was pronounced dead at the scene.
Police are treating the woman's death as unexplained and are appealing for information to help identify her.
She is white, aged 40 to 60, 5ft 6in to 5ft 8in, and of a stocky build with brown hair with blonde streaks. She was wearing a black jacket, jeans, a white blouse and pink baseball boots. She has distinctive nail artwork.
Anybody who recognises the description or who may have seen the woman in the area around Loch Morlich is asked to call police on 101.
The long sandy beach is popular with watersports enthusiasts because it has a boathouse with changing rooms. Kayaking, sailing and windsurfing are among the activities available.