Sims 4 Island Paradise: Expansion or Game Pack?

I'll be ok with either version but I really want over-water bungalows to swim out of, like in the South Pacific or the Maldives. I'd also like the cruise ship idea and lots of water activities. Put it on the edge of a glamorous city.

I might be the odd one out here and say that if they could do a quality pack on the theme at the price of a GP, I'd like that, so I'd be fine with a GP.