Lipa Noi and Taling Ngam at sunset

The west coast is the side of Koh Samui that faces the sunset, and the quiet one. Lipa Noi and Taling Ngam are long beaches on calm water, empty compared with Chaweng, and the Ang Thong islands sit on the horizon as a line of limestone shapes — a frame the east coast cannot give you. Lipa Noi's water is calm and shallow, which suits a family with small children as well as a couple walking along the edge.

Start about an hour before the sun reaches the horizon: the best light comes in the second half of that hour and the first minutes after it, when the water and the wet sand take the same colour. For a proposal this is the coast to choose; the photographer finds a stretch with nothing built behind you and keeps the islands in the frame.

The islands on the horizon are Ang Thong National Marine Park, forty-two of them, and a full boat day of their own rather than an add-on to a session. Foreign visitors pay its entrance fee, a professional shoot inside it can need the park's permission, the boats do not sail in rough weather, and the park closes to visitors for some weeks each year — check before you go. On the Gulf's calendar, the dependable months run from about January to August; October to December is the wet season, with November the wettest.