Weekend trips from Maputo

I have just arrived in Maputo with three children aged 14, 11 and 7. My husband is working here and we are going to stay for at least a year. We are looking for suggestions for places to go for weekends and half term holidays. We´ve go the longer school holidays pretty much planned but need ideas for shorter trips. Obviously there is Kruger. The kids enjoy walking, swimming and snorkeling. I would like to try white water rafting somewhere. Any good ideas?