Sexual Position in which, the female lays down, face first, on the shore with both hands by her side. Her lower back should be arched, at this point, the male who plays the role of the Cornish lifeguard, (who is just finishing his pasty), is thrusting his fallace in her anus. The added bonus is that the tide allows the female to freely and lifelessly sway back and forth in the cooling cornish tide.
First Guy: So how did the date with Mandy go?
Second Guy: Couldn't have been better, we did the Cornish Lifeguard. - All day.