Son Doong cave

This is the jaw-dropping hidden utopia that a Bradford couple chanced upon on holiday. The underground cave is showered with sunlight that pours through two huge entrances, allowing trees up to 50 metres tall to flourish. Tucked behind a mountain in Vietnam, Son Doong - meaning river mountain - has sat peacefully under the human radar for as long as records can show. Caves are defined as 'big enough for a human to fit inside'.
Towering above its minuscule explorers, this cave has shocked nature experts.