Gorgeous watercolor of water and cliffs with boats

The dark marking on the back has an ever-so-slight appearance from the front. However, it looks like it's part of the lighting of watercolor itself. The photos are slightly enhanced so it appears more obvious in the photo.

This is from a 30+ year old collection I inherited. Please see photo for condition and markings on back. This is unsigned from what I can see.

Size 12 in x 24 in