The easiest [and I think the best] way of saying it is simply 'It was fun'. You don't need to get in to a debate about whether it was fun then, but maybe now you're not so sure. Keep it simple !

Both sentences can work, but there’s a slight difference in nuance: "I think it was fun." suggests that you’re still reflecting on the experience and still hold this opinion now. "I thought it was fun." suggests that this was your opinion at the time of the trip, but it may not emphasize that you still feel that way in the present. If you still believe the trip was fun, "I think it was fun" sounds a bit more natural and immediate. However, both are correct, and the choice depends on whether you want to focus on your current or past opinion.

Both are correct, but they have slightly different nuances: "I think it was fun." suggests that you still feel it was fun, even now. "I thought it was fun." implies that at the time, you found it fun, but you're reflecting on it in the past. So, if you’re still feeling positive about the trip, “I think it was fun” works well!

If you say “I think it was fun” it implies doubt, you weren’t sure it it was or wasn’t. I would say “I thought it was fun” which suggests you had your trip, you reflected on it, your conclusion was it was fun

"Think" and "thought" are both correct. "I think" = right now at this moment I think that it was fun "I thought" = at the time of the trip, I thought it was fun Say the one that best describes your thoughts. In most cases, I would use the past tense: It WAS fun We HAD a good time You can even combine present and past tenses: "I think we had a good time."