Kunzite: "Relax? What's that? At the beach? Oh no, no, no. You're not taking me anywhere away from my work desk. Yes, I know it's vacation time, but time is money, and vacation time can still translate into work time."
Jadeite: "Water-skiing, babe-watching, beach party, babe-watching, jet-skiing, oh, did I mention babe-watching?"
Nephrite: "The stars are so bright and the skies are so much clearer in summer. I suppose I'll just become nocturnal. What? Makoto's at the beach? I'll be there in two seconds!"
Zoisite: "Zen meditation in the water is very good for the body's immune systems ... and ooh! I'm bringing my light microscope along, who knows I may find some organism to study! ... I could always go snorkelling and look for rare sea-horses ... oh the endless scientific possibilities!"
2) Winter Shitennoh ...
I'm going to vote for: Zoisite. Why? Because he can't tan and when he goes into the sun he always ends up being burnt and resembling a humanoid tomato species.
3) Troublesome Shitennoh ...
[interpret the question, anyway you like, it's just more fun the weirder the answer]
Kunzite gets into the most trouble: because the others know when to duck out of the way. Jadeite is the one who does the most horrible jokes, and Zoisite's his accomplice. Nephrite's on the sidelines laughing, but helps them a little bit by being the look-out. Poor Kunzite comes bumbling along just as the other three run away. And as the senshi wake up and discover that while they slept peacefully, tanning themselves in the sun, their clothes and bikini tops have been stolen ... who would they suspect had been the culprit ... the gaping fool Kunzite.
Well, that's it from me. Must go study Biology now, ... exam tomorrow.