Located between the towns of Vrsar and Rovinj on the western coast of Istria, Lim Bay (known in Croatian as Limski Kanal) is a unique geographic feature that resembles the fjords of Northern Europe. The name of the valley derives from the Latin term limes, meaning limit, as the bay once marked the border between the Roman provinces of Italy and Dalmatia.

This bay is technically a ria, a geological feature that forms when an unglaciated river valley becomes partially submerged, creating a coastal inlet. With a length of about seven miles (11.5 kilometers), it's the largest ria in the Mediterranean Sea. The bay once formed the estuary of a now-extinct river that carved a 22 mile (35 kilometer) long valley that now extends all the way to the central part of the Istrian peninsula. The sea depth in the bay is well over 50 feet, with steep hills on opposite sides.

A curious feature of the valley is that the vegetation on each side of the landscape differs, a result of the varying exposure to sunlight. On the north side, the flora consists of mostly evergreen plants, while the south bank is covered with deciduous trees.

Lim bay is also a breeding ground and wintering area for various fish species and is rich with mussels and oysters.