There is a beauty that lies within Grand Blue. I never thought that I'd be using that word to describe a manga like this, but it's honestly so true.

I'm going to skim over all the stuff that everyone else has already said and would recognize from the first few chapters: Grand Blue is a great comedy that has over-the-top reactions and comedy that somehow doesn't get old.
The reason for all that is definitely because the characters are fleshed out well and are all quirky enough to allow for a multitude of different scenarios and crazy things to happen. All that is great and all, but how does that make it differ from other comedy manga?

I think the big thing that sets it apart is it's unwavering focus on passion and acceptance.

Now most characters in Grand Blue are pretty unique: they all have their own interests and personalities that make them fun to read about. Yet each one also has a deep passion for something they love, whether it be diving, partying, love interests, younger sisters, etc, and they all love these things to an extreme level. People tend to avoid these types of people and call them weird, which is pretty reasonable if you think about it. But this is where the main character, Iori, differs from most people. He recognizes that it's not strange to be so passionate about something that you love, and he embraces his friends for it. He doesn't love them despite how weird they are, he loves them because they are being true to themselves.

This is the heart and soul of Grand Blue. The comedy never gets boring because it's just the characters being themselves, and that's the beauty of it all.