Croatia has three operators: HT (Croatian Telecom), A1 Croatia, and Telemach Croatia. All three provide 5G in Zagreb and 4G across the main Adriatic coastal cities and island destinations. HT has the widest national coverage. A1 Croatia has strong coastal coverage. Telemach is smaller but competitive in urban areas.
Zagreb has excellent 5G and 4G coverage throughout the city. Split has strong 4G in the old town center, Diocletian's Palace, and the ferry terminal. Dubrovnik has solid 4G in the Old Town, on the city walls, and at the cable car station. Plitvice Lakes National Park has 4G coverage in the visitor center area and along the main trail boardwalks.
The Dalmatian islands have varying coverage. Hvar Town and Hvar Island's resort areas have strong 4G from HT. Brač has 4G in Bol and Supetar. Korčula Town has 4G coverage. Vis island, more remote, has 3G to 4G in the main town. The smaller and more remote islands like Lastovo, Mljet, and outer Kornati archipelago have weaker coverage. Ferry crossings between the mainland and islands lose signal in open water. The Istrian Peninsula (Pula, Rovinj, Poreč) has excellent 4G coverage throughout.