What to See in the Hot Spring Underground: Top 10 Picks

The underground tour is a journey through time and geology. You will walk through narrow passages and see the power of nature. The city is part of the UNESCO World Heritage list for its spa culture. These sights show the technical side of that history. Here are the top things to look for during your visit.

• Best overall: The Vřídlo Geyser Base
• Best for families: Petrified Thermal Roses
• Best unique experience: The Historic Tunnels
• Best for photos: Mineral Sinter Formations

1. Name: The Vřídlo Geyser Base Type: sight Why go: This is the heart of the city. You can see the massive pipes and the raw power of the water. Best for: Engineering fans. Where: Directly under the main hall. Time: 10 minutes. Cost: Included in tour price. Getting there: Walk to the Hot Spring Colonnade. Tip: Listen to the roar of the water echoing in the chamber.
2. Name: Petrified Thermal Roses Type: experience Why go: These are famous local souvenirs. You will see how paper roses are placed in thermal water. Over time, minerals coat them in stone. Best for: Families and souvenir lovers. Where: Specialized mineral chambers. Time: 5 minutes. Cost: Tour ticket required. Getting there: Part of the guided route. Tip: You can buy finished roses at the gift shop upstairs.
3. Name: Mineral Sinter Formations Type: nature Why go: The hot water leaves thick layers of minerals on the walls. These look like colorful cave curtains. Best for: Photographers. Where: Along the tunnel walls. Time: 5 minutes. Cost: Part of the tour. Getting there: Follow the guide through the lower levels. Tip: Look for the different colors caused by various minerals.
4. Name: The 19th-Century Tunnels Type: sight Why go: These brick tunnels show how Victorian engineers managed the spring. They are beautifully preserved. Best for: History buffs. Where: The oldest section of the tour. Time: 10 minutes. Cost: Included in ticket. Getting there: Accessed via the Hot Spring Colonnade underground tour. Tip: Notice the craftsmanship of the old masonry.
5. Name: Thermal Water Pipelines Type: sight Why go: See the modern system that sends water to local hotels. It is a complex network of steaming pipes. Best for: Technical minds. Where: The utility corridors. Time: 5 minutes. Cost: Included. Getting there: Middle section of the tour. Tip: Do not touch the pipes as they are very hot.
6. Name: Underground Foundation Pillars Type: sight Why go: The Colonnade is built on massive supports. You can see how the building stays stable over the hot earth. Best for: Architecture lovers. Where: Main structural area. Time: 5 minutes. Cost: Included. Getting there: Follow the marked path. Tip: Compare these to the modern glass structure above.
7. Name: Thermal Algae Colonies Type: nature Why go: Rare organisms live in the hot, mineral-rich environment. They create bright green and orange patches. Best for: Science enthusiasts. Where: Near the water outlets. Time: 3 minutes. Cost: Included. Getting there: Visible from the walkways. Tip: These plants only grow in these specific conditions.
8. Name: Water Collection Wells Type: sight Why go: These deep wells collect the water before it is pumped. They look like dark, steaming pools. Best for: Atmosphere. Where: Lower basement levels. Time: 5 minutes. Cost: Included. Getting there: Guided access only. Tip: Watch the steam rise from the surface.
9. Name: Historic Maintenance Equipment Type: sight Why go: See the old tools workers used to clean the pipes. Mineral buildup is a constant challenge. Best for: Learning about city maintenance. Where: Small museum niches. Time: 5 minutes. Cost: Included. Getting there: End of the tunnel circuit. Tip: Imagine the hard work of manual cleaning in the heat.
10. Name: St. Mary Magdalene Crypt Type: day trip Why go: Located right next to the spring, this crypt holds historic remains and unique geology. It complements the spring tour perfectly. Best for: Culture seekers. Where: Directly across from the Colonnade. Time: 30 minutes. Cost: Separate small fee. Getting there: Walk 50 meters from the spring exit. Tip: Check opening hours as they vary seasonally.

Planning Your Hot Spring Colonnade Underground Tour

Visiting the underground requires some preparation. Tours are usually guided and last about 45 minutes. You should check the unique places in Karlovy Vary for booking tips. The air downstairs is very humid and warm. It feels like a natural sauna. Wear light clothing even in winter. The floors can be slippery from the mineral water. Always wear sturdy shoes with good grip. Most tours are in Czech, but audio guides are often available. Book your tickets in advance during the summer months. This is one of the most popular attractions in the city.

More Unique Experiences Near the Hot Spring

After your underground adventure, explore the surface. The Hot Spring Colonnade itself is a masterpiece of functionalist design. You can taste the water at different temperatures. Each fountain has a slightly different mineral balance. For a great view, follow a Diana Observation Tower guide to see the city from above. The walk through the woods is refreshing after the humid tunnels. You can also visit the nearby Market Colonnade. It features beautiful wooden carvings and more healing springs. Karlovy Vary is a city built on water, and every corner proves it.