Save $400 by going to the beach … I wish it were always this easy!

Hilton’s trying to make it as easy as possible for you to soak up the sun this summer. Its new deal in Puerto Rico will set you up with a free fourth night if you pay for three. Even better: the three nights that will cost you only start at $139 each. All in, you’re saving up to $400 a trip. Resort credits are offered for golf, dining, spa treatments and other activities.

And, it keeps getting better. You could also pick up a bonus certificate for a free night down the road if you book by July 15, 2009.

The four participating hotels are solid: El San Juan Hotel & Casino, The Waldorf Astoria Collection; El Conquistador Resort & Spa, The Waldorf Astoria Collection; Conrad San Juan Condado Plaza and Caribe Hilton, San Juan. So, it’s not like you’re being given a low price at a low-end hotel. This is strictly top shelf.

The catch? The promotion’s only good through the end of September.