Backstroke start technique: https://www.youtube.com/watch?v=xwq-IsGNa28
Backstroke flipturn technique: https://www.youtube.com/watch?v=B-WNtRGwSjQ
Underwater dolphin kicks can be done on your front, back, or (I guess) side, so it also works for backstroke. And the way that starts and turns work in backstroke still puts you underwater at the start of each lap.
Backstroke start technique: https://www.youtube.com/watch?v=xwq-IsGNa28
Backstroke flipturn technique: https://www.youtube.com/watch?v=B-WNtRGwSjQ
Underwater dolphin kicks can be done on your front, back, or (I guess) side, so it also works for backstroke. And the way that starts and turns work in backstroke still puts you underwater at the start of each lap.