Can I go on a bachelor or bachelorette trip as a Muslim?

It depends on what the trip involves. A weekend away with friends to celebrate someone's wedding is fine in itself. But the classic bachelor or bachelorette trip, built around drinking, clubs, strippers and flirting, is not something a Muslim can join. Many converts go for the parts that are halal and skip the rest.

What makes the usual version a problem

The issue isn't travel or celebrating a friend. It's what a typical stag or hen weekend is planned around: heavy drinking, nightclubs, strip shows, and a "last night of freedom" attitude toward flirting or hooking up. Islam forbids alcohol and gambling, and it also tells us to stay away from anything that leads toward zina, not just zina itself:

وَلَا تَقْرَبُوا۟ ٱلزِّنَىٰٓ ۖ إِنَّهُۥ كَانَ فَـٰحِشَةً وَسَآءَ سَبِيلًا "And do not approach unlawful sexual intercourse. Indeed, it is ever an immorality and is evil as a way." Quran 17:32

Popular destinations like Las Vegas or Amsterdam are often chosen for exactly these reasons. See Can Muslims go to Las Vegas?

Company shapes you

The Prophet ﷺ compared a good friend to a perfume seller and a bad companion to a blacksmith's bellows: you either come away smelling nice or with burnt clothes (Sahih al-Bukhari 2101). He also said, "A person is upon the religion of his close friend, so let each of you look at whom he befriends" (Sunan Abi Dawud 4833). A weekend where everyone gets drunk together is a lot of pressure, especially in your first years as a Muslim.

Ways to still celebrate your friend

Join the daytime plans. Brunch, a spa day (same-gender), hiking, go-karting, an escape room or a city tour are usually fine.
Leave before the bar crawl. You don't have to sit in a club with a soda all night. See Can I go to a bar with friends if I only drink soda?
Offer to plan one part. Suggest a dinner, a cabin weekend or an activity everyone can enjoy, so you're part of the memories.
Give a thoughtful gift or write a speech for the wedding instead.

Telling your friends

Be honest and warm: "I really want to celebrate you, but I don't drink or do the club stuff anymore. Can I join the dinner and the activities?" Most friends respect a clear, kind answer more than a vague excuse. If the whole trip is about partying, it's okay to send love and skip it. The same goes for group traditions at university. See Can I join a fraternity or sorority as a Muslim?

If it's your own wedding

You can have a halal version: a same-gender weekend away, a nice dinner, a fun activity day. Many Muslim brides hold a henna night with female friends and family, and grooms often go on a trip or game night with the guys.

Key points

Traveling to celebrate a friend is fine in itself.
Drinking, clubs, strip shows and flirting are not.
Join the halal parts and leave before the rest.
A kind, honest explanation usually goes down well.

Tip: Ask the organizer for the plan before you book. If the itinerary is mostly bars, offer to host a welcome dinner on the first night instead, so you still play a real part.