Seaside Romance Prom Ideas Needed...

I really need help with decorating ideas for my high school prom. Our theme is seaside romance which seems easy enough, but the place we are having prom has really high ceilings, walls which we cannot hang anyhing on, but can lean things against, but there are two really nice staircases witch meet in the middle of the room. If you have anything that you can offer me please do so... Thanks