Slagbaai park... worth doing once... The vistas on the East side are beautiful. I wish you could turn around at Malmok. The road from Wayaka back to the entrance is literally a pain in the a**.
The "pain" of the drive is reduced - or amortized, really - if you get there when the park opens and bring at least three tanks each. Bring lunch and make a half-day of the trip. Given the need tor surface intervals between dives, the drive through the park can be a useful diversion rather than simply "the ride out" of the park.