About Us
Since 2012, Undertowashhollow has been Tokyo's most trusted specialist in professional caving and underground adventure equipment. We are cavers first, and retailers second.
Equip Every Descent. Enable Every Explorer.
Undertowashhollow was founded by a small group of dedicated spelunkers who were frustrated by the lack of serious caving gear available in Japan. Import shipping times, incorrect sizing, and a complete absence of expert advice had cost our founders — and many others — time, money, and occasionally their safety.
Our mission from day one has been simple: source, test, and stock the world's finest caving and underground adventure equipment in a single Tokyo location, staffed by people who actually use the gear.
Whether you are rigging a forty-metre vertical pitch in Yamaguchi, squeezing through a 30-centimetre lava tube in Fuji, or planning a multi-day underground river expedition in Southeast Asia, we have the equipment and the knowledge to get you there safely.
Our Core Values
Every decision at Undertowashhollow — from which brands we stock to how we train our staff — is guided by three non-negotiable principles.
We will never stock an item we consider unsafe, regardless of demand or margin. Every product undergoes internal review before it reaches our shelves. Customer safety is not a selling point — it is a baseline.
Our staff are required to maintain active caving practice. We attend expeditions, take technical courses, and review new gear in real cave environments. Our recommendations are informed by direct experience, not manufacturer literature.
The underground environments we equip people to explore are irreplaceable. We promote Leave No Trace caving ethics, support speleological research, and donate a portion of annual revenue to cave conservation organisations in Japan and globally.
Shibuya Showroom & Headquarters
Our flagship store at 1-2-3 Shibuya, Shibuya City, Tokyo 150-0002 is Japan's most comprehensively stocked caving equipment destination. Over 500 SKUs are on display across 200 square metres of showroom floor, including full-length rope displays, helmet and harness fitting stations, and a dedicated lighting test room.
We are open Tuesday through Sunday, 10:00–19:00. Walk-in consultations are welcome. For full expedition planning sessions, we recommend booking a 45-minute gear consultation appointment in advance — call us at +81 3-5491-5260 or email info@undertowashhollow.com.
Our online shop carries the same inventory and ships nationwide with same-day dispatch (orders placed before 14:00 on open days) and international shipping via Japan Post EMS and DHL Express.
Meet the Team Behind Your Gear
Undertowashhollow is staffed entirely by active cavers and underground explorers. This is not a retail job for us — it is a calling. Every member of our team brings direct expedition experience and professional certifications.
Hiroshi Nakamura pioneered technical caving in Japan during the 1990s and has led over 200 documented expeditions across Asia, Europe, and North America. He holds IRATA and ASSE rescue certifications, and is a former chair of the Japanese Speleological Society.
Yuki Tanaka spent eight seasons as a professional cave guide in Thailand and Laos before joining Undertowashhollow in 2018. She specializes in expedition kit building and leads our monthly SRT (Single Rope Technique) training courses.
Kenji Sato manages inventory, quality control, and staff certifications. Every product that passes Kenji's inspection has been personally tested underground. He is PADI Advanced, UIAA certified, and an active climbing and caving instructor.
Conservation & Stewardship
We believe cavers have a responsibility to preserve the cave systems we explore. Undertowashhollow commits 5% of annual net revenue to cave conservation projects, speleological research, and environmental restoration.
Recent contributions include funding for the restoration of Akiyoshi-do cave ecosystem monitoring, support for undergraduate speleology research at Kobe University, and donations to the Japan Cave Protection Society.
We are also proud sponsors of caving clubs, rescue teams, and university expedition programmes across Japan and Asia. Every cave system and every caver we equip is part of a larger commitment to sustainable underground exploration.
The Road Ahead
Undertowashhollow continues to grow, but we are committed to staying true to our core mission: equip explorers with the best gear on Earth, staffed by people who actually know what they are selling.
We are opening specialist caving shops in Taiwan and South Korea to better serve international cavers across East Asia.
Multi-day SRT, canyon rescue, and cave diving certification courses taught by our team and visiting international experts.
Custom harnesses, oversuits, and specialized equipment designed by cavers for the specific demands of Asian cave systems.