Leading Shillong adventure company Pioneer can take you diving in the hills! Open-water dives (per person ₹3500) are available at its Shnongpdeng adventure camp near Dawki, where the Umngot River offers up to 10m visibility. Other activities include snorkelling, climbing, rafting, canyoning, cliff jumping and kayaking. Overnight camping packages (per person around ₹10,000) allow you to sample a bit of everything.
Pioneer also operates a fearsome zipline flying 800m across the 350m-deep Mawkdok Dympep Valley, 30km south of Shillong on the Cherrapunjee road (₹800 per ride, operating 10am to 5pm except Tuesdays).