I visited this park during my recent stay at Diani Beach and would recommend it as an attraction for anyone staying in, or near, Mombasa. It is a former cement quarry which has been retored into a wildlife park to remarkable effect. It has a website which provides information - http://www.lafargeecosystems.com/main/index.php
The array of wildlife is vast. Strolling along a path we were quite taken aback to find a giraffe in front of us! We soon discoverd that it was accompanied by more, including young, just off the path. The less friendly animals are in secure enclosures. A cafe is situated above a pond which contains crocodiles. A highlight is witnessing the feeding of the hippos. When the food is provided they leave the water. A word of warning - make sure you are not watching from beneath a tree if a cerain monkey climbs up it. The crocodiles are fed after the hippos. A slight criticism is that the signing could be a bit better. The Park is vast and we had difficulty finding the exit.
Haller Park is situated near Mamba Village which is a must if crocodiles are your main attraction. To get the best out of both, it would be advisible to devote the best part of a day to each.