As a tourist, the least you could do is not make things worse. One of the easiest ways to do this is by doing without plastic packaging in the first place. Luckily the World Wide Fund for Nature (WWF) has a small guide on just this topic.
It recommends that travelers take along a reusable water bottle or an insulated thermos from home so that they don't have to buy plastic water bottles at their destination. According to the WWF, there are also reusable bottles with an integrated water filter.
Reusable food containers and cutlery can also be taken along, as can a cloth shopping bag. If you want to really avoid plastic, you should also pass on cosmetics and sunscreens that contain microplastics.
Booking an accommodation that has been deemed sustainable by a reputable certification program can also help reduce plastic use.
Once at the destination, travelers should ask about the quality of the tap water. In some places, tap water has a reputation as being undrinkable even if in actuality it is not true, says the WWF.
Public drinking fountains are a great source for refilling bottles.
If you want a gold star when it comes to avoiding plastic waste, then you won't be able to visit snack kiosks or quick-serve restaurants that serve food on disposable plates and provide plastic cutlery.
Unpackaged food should be given preference over packaged products.
And it almost goes without saying: You should avoid leaving your trash somewhere where it could end up in the ocean at some point.