"...But Hemel doesn't have any cliffs."
(true enough, though there are a lot of steep hills)
(Um, no. It does have an escarpment off downland, which people paraglide, etc from, but it's hardly a cliff)
"Oooh I want to do that! But without a parachute."
Okaaay. Exactly what activity can be done with a parachute, where there is a possibility of doing it without one? Short of suicide that is.