What are the best day trips from Zagreb?
Hey, there are plenty of them, most notable would be Ljubljana, Lake Bled, Plitvice Lakes, Samobor, Rijeka, Opatija, Krk. Depending on what you want you can sightsee nature, or go for a swim, about 2.5 hour away from Zagreb. Below are some great guides so check them out.
Lake Bled Day Trip from Ljubljana Guide
Ljubljana Slovenia, Top Things to do, Guide for day trip from Zagreb
Things to Do on Krk Island, Croatia
Plitvice Lakes Guide by a Local (Which entrance, trail to choose, prices etc.)
Rijeka Croatia Things to Do: Is it Worth Visiting?
Opatija guide (Day trip from Zagreb to Croatian coastline)