Nthabiseng is watching waves in a pool. She counts 54 crests moving past a fixed point in 57,7 seconds. The crest-to-crest distance is 18,0 cm and the crest-to-trough height is 8,2 cm.

The diagram below (not to scale) shows some of these crests.​

Nthabiseng is watching waves in a pool She counts 54 crests moving past a fixed point in 577 seconds The cresttocrest distance is 180 cm and the cresttotrough h class=