We found a campsite on the opposite side of the river to Antwerp city centre. The campsite was very basic but the staff were very helpful, so we decided to stay for a few days. To get to the city we had to cross the river via the Sint Anna pedestrian tunnel. The escalators/lift take you down 31 feet below the water and you literally walk underneath the river for 600 metres to reach the centre. It was a surreal experience for us, but so clearly just the norm for Belgian people, we fell in love with the city from the moment we walked out of that tunnel.