The Herts Young Mariners Base (HYMB) is an outdoor activity centre in Cheshunt, Hertfordshire that offers a variety of exciting options to get you out and about. Whether you’re a seasoned adventurer or a complete beginner, HYMB has something for everyone. HYMB caters to all ages and abilities, so you can be sure to find outdoor activities that suit your interests. Most activities require booking in advance, so be sure to check availability.