About 70 kms (48 miles) from Karachi on the left is Haleji Lake, a waterfowl sanctuary and a birdwatcher's paradise. A 5 kms track leads to the Lake.
One can get out of car, stretch a bit, observe and photograph resident waterfowl (migratory waterfowl does not arrive till December) and take a 10 km circumferential drive before hitting the Highway again.
For more information, see my tip on off the beaten path in Pakistan page.
Haleji originally was a salt-water lake which was formed by seasonal water, collecting in a depression. During World War II, additional water was required for troops stationed at Karachi. Salt water was drained out and an embankment was constructed around the lake which was fed by fresh water through a canal. Resultantly, Haleji became one of the major sources of water supply to the increasing population of Karachi as well as an exquisite refuge for waterfowl.
A water reservoir, home to Siberian migratory birds from November till February - birds lover paradise in these months. Some crocodiles as well, and fishing.
For more info, see my Thatta pages