On deadly tides / Elizabeth J. Duncan.

Enhanced descriptions from Syndetics:

Penny Brannigan is the owner/operator of a Welsh seaside spa, a talented watercolor artist--and an amateur detective. But mayhem is far from her mind as Penny commences a painting holiday on the idyllic island of Anglesey, off the coast of North Wales. Penny takes a deep breath of island air and sets out her brushes to capture the stunning scenery--a charming black-and-white lighthouse, wide pebble beaches, stunning sea and mountain views. Soon, she's painting the island red with a ruggedly handsome wildlife photographer who adds a dab of romance to her palette. But the sunlit scene turns dark when Penny, peering down from a high cliff, spies the body of a popular hotel manager on the secluded beach below.

The receding tide threatens to pull him out to sea, never to be found. Fortunately, with the help of a strong wind blowing inland, Penny is just barely able to pull the unfortunate victim onto dry land. An accident? The medical examiner seems to think so. The postmortem reveals that the victim's injuries were consistent with a fall from a great height, so everyone seems to agree that the cliff has claimed a hapless hiker. Still, Penny suspects it may be an artful ruse. Peering into the hotel manager's petrifying past, Penny paints a picture of present-day perfidy. But will she survive this brush with danger?