The working harbour at Al Khums is the heart of the town itself, away from the Roman ruins. Small fishing boats come and go through the day, and the seafront corniche offers an agreeable walk in the evening when the heat has subsided. The fish market near the harbour is busiest in the morning and has fresh Mediterranean catch — if you can negotiate with a local family or a small restaurant, the fish is outstanding.
The harbour area is where Al Khums is most itself, distinct from the ruins that bring most visitors. The low-rise streets behind the waterfront preserve a traditional Libyan coastal town character: whitewashed walls, workshops, small mosques, and the ordinary rhythm of daily life in a Mediterranean port city. It's a good hour's walk to explore without a specific destination.