Drive via US-290 E and I-35 N from 77406 to Natural Bridge Caverns — Houston-area departure; leave at 5:00 AM for roughly 3–3.5 hours, allowing for traffic and a breakfast stop; arrive early, park on-site, and reserve the first available cave tour.
Natural Bridge Caverns — north of San Antonio; explore a guided underground cavern tour and allow 9:00–11:30 AM including check-in and walking time.
Tavern at Gruene — Gruene Historic District; enjoy a relaxed Texas lunch for approximately $20–35 per person, around 12:00–1:00 PM.
San Marcos Premium Outlets — north San Marcos; shop the outlet complex with 1:30–5:00 PM available, prioritizing stores before the return drive.
Drive via I-35 S and US-290 W back to 77406 — San Marcos to home; depart around 5:00 PM for approximately 2.5–3 hours, with a brief rest or meal stop near the route if needed, targeting arrival by 7:00–8:00 PM.
Leave 77406 promptly at 5:00 AM, taking US-290 E toward Austin, then I-35 N and local roads to Natural Bridge Caverns. Plan on roughly 3–3½ hours, plus a quick breakfast or coffee stop; Sunday traffic is usually manageable, but allow extra time near Austin and San Antonio. Arrive with your reservation confirmation ready and park on-site. The first available guided cave tour is ideal—allow about 2½ hours for check-in, walking, and the tour. Admission commonly runs about $30–$45 per person depending on the tour, and the caverns are cool, damp, and uneven, so wear supportive shoes and bring a light layer.
After the caverns, drive about 25–30 minutes to Tavern at Gruene in the Gruene Historic District, aiming for lunch around noon. This is a good place to slow down after the morning underground: expect hearty Texas fare and approximately $20–$35 per person. If you have a few spare minutes, take a short look around the historic district before continuing, but keep the stop to about an hour so you reach the outlets during the main shopping window.
Head roughly 20 minutes south to San Marcos Premium Outlets for shopping from about 1:30–5:00 PM. The complex is large, so park near the stores you most want to visit, wear comfortable shoes, and make a short priority list before wandering; three hours goes quickly. Many stores generally operate into the evening, but confirm Sunday hours and any desired cave-tour availability in advance, especially because September heat can make walking between buildings tiring. Around 5:00 PM, begin the return via I-35 S, connecting to US-290 W toward 77406. Budget approximately 2½–3 hours, with a brief rest or meal stop near the route if needed; a 7:30–8:00 PM arrival is more realistic if traffic builds around San Antonio or Austin.
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