Mariya Koroleva: Synchro swimmer says 'underwater you feel like you're dying'

Above the surface it is all smiles. But according to US Olympic synchronised swimmer Mariya Koroleva 'underwater it feels like you're dying'.

The 22-year-old immigrated to the US from Russia when she was nine.

In California, she decided to try synchronised swimming as a way to fit in. She fell in love with the sport and finally qualified for the national team after getting her US citizenship.

The BBC's Franz Strasser entered the water to find out just how exhausting Koroleva's training is and to hear why she remains deeply connected to her Russian roots.