We made a few mistakes while reaching Yamuna Biodiversity park, so I thought I could take a few pictures to help others reach it (many were taken on the way back so are unclear, still they might help).
The basic route as currently given on websites and blogs is something like this, directions to Yamuna Biodiversity Park, Delhi:
Go along the ring road straight down ISBT (kashmere Gate), for a couple of kilometres beyond Majnu Ka Tila. Go towards Wazirabad, till you come to the big Wazirabad crossing (for ID – there is short divider here which splits the straight-going lane into two). Carry on straight and then take a right after the Wazirabad crossing. Go across a nalla. Once on the other side, take a left so that you are running parallel to the nalla. Now, look out for and follow the Yamuna Biodiversity Park signboards. Take a right again which will lead you to the Yamuna Biodiversity Park.
HERE ARE THE UPDATED DIRECTIONS FOR YAMUNA BIODIVERSITY PARK:
Go straight along the Ring Road pass ISBT, keep going straight till you come to the Wazirabad Crossing.
On the left it says Wazirabad!
The Road Directions near Wazirabad crossing!
At this point a divider appears on the road that splits the road in two, however there is a lot more too. There is construction happening on a large scale, and there are screening boards on both sides.