Jerba is the most obvious excursion from Zarzis, 20 minutes away by road across the ancient Roman causeway. The island has more tourism infrastructure than Zarzis and more to see: the El Ghriba synagogue, the Houmt Souk old town with its Ottoman fort, and excellent fish restaurants. Zarzis makes a quieter base than the island's resort zone if you want to visit Jerba's sights without staying inside the tourist bubble.
Jerba Day Trip
A story
The island of Jerba lies 20km from Zarzis by road, connected by a Roman-era causeway that is still in use today — one of the longest surviving causeways from antiquity, running about 6km across the shallow gulf. Jerba is home to the El Ghriba synagogue, the oldest synagogue in Africa and a major pilgrimage site, as well as a significant Berber heritage, the Houmt Souk market town, and a long tradition of Jewish-Muslim coexistence that sets the island apart from most of the Mediterranean.