An hour and a quarter inland from Split, the karst does something theatrical. On the edge of the small town of Imotski, the ground simply opens — twice. One chasm holds a lake you can swim in, reached by a path that zigzags down the cliff. The other is a red-walled abyss so deep that the town’s entire bell tower would vanish into its shadow many times over. Almost no foreign visitors come. This is the strangest great day trip in Dalmatia.
Modro jezero: the lake you climb into
Blue Lake sits in a sinkhole right behind Imotski’s main street. A stone path — built a century ago and recently restored — switchbacks down the cliff face, and ten minutes later you’re standing on the shore of a lake at the bottom of the earth, cliffs rising all around like an amphitheatre roofed with sky. In summer, when the level is right, locals swim here daily; there are few stranger and better places on this coast to take a dip.
A lake with moods
Modro jezero’s party trick is its water level, which can swing by tens of metres between seasons. In wet springs it laps near the top of the path; by late autumn in dry years it can vanish entirely — and when it does, the town famously plays a football match on the dry lakebed, one of Croatia’s oddest traditions. Whatever level you find is the correct one: the lake is a living gauge of the karst beneath.
Crveno jezero: the one you only look into
Ten minutes’ walk away, Red Lake plays by different rules. There is no path down and never will be: the sinkhole’s rust-red walls drop near-vertically to a lake whose surface lies far below the rim, with roughly half a kilometre from lip to lakebed — among the deepest karst features in Europe. You stand at the viewpoint, hold the rail, and feel your sense of scale recalibrate. Photographs flatten it; your stomach won’t.
The town between the lakes
Imotski itself deserves the middle of your day: a steep old town of pale stone crowned by the Topana fortress directly above Blue Lake, cafés on the main street where the pace is fully inland, and Zagora cooking that assumes you’ve earned your appetite — pršut, lamb, uštipci fritters. This is the Dalmatia of the interior: drier, prouder, quieter, an hour and a world from the Riva.
The practical page
The motorway does most of the work: Split to Imotski is about 75 minutes by car, making this one of the easiest inland trips there is. Go in the morning for the descent to Blue Lake (shade and cooler air in the sinkhole), lunch in town, Red Lake’s rim in the afternoon. Wear shoes with grip for the lake path and bring water; there are no kiosks at the bottom of the earth. Drivers can loop home via the Biokovo foothills and the coast — Makarska is on the way — or pair Imotski with the Cetina country for a full inland day.
Why it’s worth turning your back on the sea
Because nothing else near Split rearranges your sense of the landscape like standing inside one sinkhole in the morning and on the rim of a deeper one after lunch. Among all the day trips we recommend, Imotski is the one guests come back from saying “why does nobody talk about this?” Start early from the old town and you’re home for the evening swim.