Rodah Chiawa and her friend Hope Ngulube cling to each other in the small outdoor pool, laughing nervously. It is only the second time they have been in a swimming pool, so the instructor tells them to put on lifejackets before swimming to the deep end. Cue much splashing, squealing and cheers from their teammates.
For the next half hour the group practise swimming on their backs, holding their breath and treading water. After a sweltering morning learning to handle tracking dogs in the Lower Zambezi national park, they welcome the chance to cool off and have fun doing relay races.
Chiawa, 25, and Ngulube, 20, are being put through their paces as part of an intense, military-style selection process