San Marcos sits on I-35 between Austin and San Antonio, but the freeway is not the reason to stop. The town is built around the San Marcos Springs, where clear water rises from the Edwards Aquifer and becomes one of the most loved swimming and tubing rivers in central Texas.
The best day here starts near Spring Lake, where glass-bottom boats still cross the old Aquarena Springs water. From there the river runs past parks, low dams, swimming holes, and lawns busy with students from Texas State University. In summer, the water gives San Marcos a stronger identity than many larger Hill Country towns.
Away from the river, the courthouse square has bars, coffee, old storefronts, and enough student energy to keep it from feeling like a preserved museum. Wonder World Cave adds a quirky geological stop on the Balcones Fault, while Old Main on the Texas State campus gives the town its hilltop landmark.