A surge in global tourism is placing unprecedented pressure on the world’s karst landscapes, with new scientific evidence warning that these fragile ecosystems are nearing critical levels of degradation. The findings come from a study by karst specialist Nadja Zupan Hajna, published in October 2025 in the journal Nature-Based Solutions under the title “Caves and Karst in Global Sustainability: The Case for an International Day.”
The study highlights that growing tourist numbers, expanding cave-tour infrastructure, and unregulated recreational activities are accelerating environmental damage in karst regions across Asia, Europe, and Latin America—areas that collectively support drinking water supplies for hundreds of millions of people.
Karst landscapes, formed through the dissolution of limestone and other soluble rocks, are among the world’s most sensitive geological systems. Their porous subterranean networks enable pollutants to travel quickly through groundwater channels, while cave ecosystems harbor species that can survive only within extremely narrow environmental conditions.
According to Hajna’s research, visitor numbers in several globally known cave destinations have doubled or even tripled since 2018. “Tourism pressure is now a leading driver of karst degradation worldwide,” Hajna warns in the report. “These environments are not just tourist attractions—they are living water systems that underpin regional sustainability and human survival.”
Multiple Damage from Tourism
The study documents multiple forms of damage linked to tourism growth, including accelerated erosion of cave floors and walls, disruption of humidity and temperature balances essential to cave fauna, and increased contamination from microplastics, sunscreen chemicals, and untreated wastewater from tourism facilities.
In Southeast Asia, environmental agencies have recorded spikes in sedimentation and water cloudiness in underground rivers. European conservation groups have similarly raised concerns about carbon dioxide accumulation, artificial lighting, and noise pollution inside heavily visited caves—factors that disrupt the breeding cycles of endemic species and threaten long-term biodiversity.
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The expansion of hotels, access roads, and parking structures near karst zones has also altered groundwater flow and destabilized slopes in several countries, compounding the environmental stress. “Damage in one location can spread quickly across an entire karst system,” Hajna notes. “A contaminated sinkhole may pollute drinking water kilometers downstream.”
Some regions have responded by introducing visitor caps, restricting access to sensitive chambers, or requiring guided-only cave tours. However, Hajna argues that these measures remain “fragmented, inconsistent, and often reactive rather than preventive.”
Save Karst from Tourism Boom
The study calls for governments and tourism authorities to incorporate karst conservation into national policies, mandate ecological assessments for new tourism infrastructure, and strengthen wastewater management near karst zones. Public education on responsible cave tourism is also identified as a crucial step in reducing the human footprint.
“Karst systems cannot regenerate at the pace they are being harmed,” Hajna concludes. “Without coordinated protection, these geological treasures—and the water they provide—may be lost to future generations.”
With global tourism numbers expected to continue rising in the post-pandemic era, researchers warn that the world’s karst landscapes could face irreversible ecological damage within a generation if no integrated management framework is implemented. (Sulung Prasetyo)
