Beach Episode/Fan Works

Examples of Beach Episodes in Fan Works include:

There is one of these in the Fanfiction More Than Human that actually advances the plot.
Used in Seduction to advance the plot.
In Kyon: Big Damn Hero, the SOS Brigade has one of these arranged for the weekend after Kyon went back in time to create a massive stable time loop and getting 96 on a Math test.
Ultimate SpiderWoman: Change With the Light: In between fighting supervillains and trying to juggle everything going on in her personal life, Mary Jane Watson needed a break. She got one at first... but then one of her enemies showed up and she was forced to don her Spider-Woman costume anyway. Go figure.
The fan comic Roommates has one too. Being heavy on Fan Service this surprises nobody.
A beach episode takes place during the third chapter of Isekai by Moonlight. When four characters were sent to another dimension, they went to the beach for the narrator's birthday. Ami and Makoto wore bikinis; nobody noticed what the narrator wore.