Take the kids to Jetty for some fresh air and sunshine. They'll have a great time trying to find fish splashing in the waters below or boats way off in the distance.
You'll soon see why this Swakopmund waterside attraction is popular with travelers. If you're looking for other things to keep you busy, Swakopmund Beach, The Dome, and Swakopmund Lighthouse are in this area as well. They won't take you very long to reach from Jetty.