You could try modeling both the beach and the sea. I would start with a simple plane for the beach, and then just sculpt it with ribbon tools. Some grass can be scattered. As for the sea, I would start by creating a circle (yes, a circle!), then converting it to poly, and then displacement/bump.
You can also take a look at Ludvik’s dune tutorial:
In most cases interior shots can hugely benefit from ground plane as well, even if it’s not visible directly. Light bounced from the ground and then entered the room, can dramatically change look and mood of picture.