Toddler miserable on vacation

I haven't taken my kiddo (now 2.5 years) on an international trip since he was a baby (that trip was wow good) and thought I'd do something with him now that he's a bit older and before Ihave my second baby in a few months. Decided to just go to a resort on a tropical island close to home so the time difference isn't too big and the plane ride isn't so long,.

Well, things aren't going well into the third day. He was miserable on the plane ride and now absolutely doesn't want to do anything (just cries/whinges when we try to do activities). He keeps saying he wants to go home and has a tantrum lasting an hour when we try to leave the hotel room. We have to force him out of the room kicking and screaming until he eventually accepts whatever thing we're doing that day. He'll enjoy it for a bit but after maybe 30 minutes will become very whiny. Also won't eat much.

I think he may be overwhelmed at being taken out of his confort zone and usual routine, even though we've been talking about going on a trip for weeks now. I'm very disheartened because I just wanted to have a fun family vacation and we're all just miserable and counting down the days to go home.

We have another 3 days here and I really want to make some good memories - does anyone have any tips on how to get kiddo to warm/cheer up?