Let's cut right to the chase: should you watch this show?
Hell Yes.
Grand Blue is the first anime in a while that has centered its story around the college life (last I have seen being Golden Time), but with this time, it embraces the partying aspect of it... a lot. It is a show with a really awesome cast that all interact in different and funny ways with each other, making for some seriously hilarious jokes throughout the show. Seriously, I've almost died of laughter from this show many times.
While Grand Blue is a comedy, its storytelling is also decent, as we learn how serious diving actually is from the supporting cast, and the beauty it can entail as well.
Overall, Grand Blue is just a stellar anime and a perfect cleansing anime after a long day's work.