An "Under the Sea" birthday party theme makes a fun occasion for teens in the summer. Based around a pool, it's ideal for younger teens and older tweens. It's easy to theme the decorations for the crowd; sharks themes or mermaid themes are always popular.
Because younger teens aren't the best at socializing, it's good to have some pool party games on hand in case things start to slow down a bit. Setting up a food buffet far enough away from the pool to let people eat comfortably without getting wet is helpful. Themed foods include gummy fish and fish-shaped crackers. Possible party favors include sunglasses and beach towels.
A Hawaiian luau theme works well for older and younger teens alike. This can take place in the day or in the evening, when dusk is approaching. If it's getting darker, tiki torches and palm trees create a festive atmosphere. Putting guests in grass skirts and holding a hula contest breaks the ice for many groups. Leis make a fun favor, and a table where people can make lei bracelets is a nice touch. Hanging streamers in blue, aqua and green colors around the pool adds to the ambiance, while white lights for an evening party give the secret "lagoon" a glowing vibe.