Complex sentence: The creation of the North-west Nelson Forest Park in 1965, that was to become Kahurangi National Park in 1996, led to the rediscovery and improvement of the track, which is now tramped by thousands of people every year.
Split into simpler sentences: The creation of the North-west Nelson Forest Park in 1965, which became Kahurangi National Park in 1996, led to the rediscovery and improvement of the track. The track is now tramped by thousands of people every year.