'This is NOT a filter': Russian swimming champ Efimova takes late-night dip in incredible bioluminescent ocean (VIDEO)

Six-time world champion Yuliya Efimova has given fans another glimpse into her idyllic lifestyle during quarantine by joining friends for a twilight boat party and night swim in bioluminescent waters near her base in California.

Having demonstrated her breaststroke technique from her Los Angeles kitchen table and shown off her outdoor swimming pool in previous videos, the two-time silver medalist at the 2016 Olympic Games went a step further in her latest clip, setting off by boat to explore the bioluminescent waters of the surrounding coast.

Joined by fellow swimmers Alena Rumiantceva and Lisa Bazarova, Efimova filmed the natural phenomenon of the blue-lit waves to her Instagram following of more than 200,000 before perching the camera on the deck, holding hands with her friends and jumping off the back of the boat in her swimwear.

"Hands down one of the coolest things I've ever experienced," she admitted, marveling at the illuminating effect caused by plankton.

"Yes, it happens. This is not a filter and not a backlight – this is real nature."

Russian-born Bazarova said that "all days are like Saturday" during the public quarantine over Covid-19, enforced as part of attempts to stop the spread of a disease which has caused almost 70,000 confirmed deaths in the US to date.

The student athlete at the University of Texas posting a photo of herself lounging on a pool float in blissful surroundings alongside Efimova, Rumiantceva, Bazarova and friend Francie Giovino.

Efimova also revealed her taste for pop music, soundtracking her clips with Shaggy hit 'Angel' and Norwegian DJ Kygo's 'Freedom' as the trio laughed and screamed during their sea trip.

The 200m breaststroke champion at last year's World Championships in Korea has frequently posted snaps of life in lockdown in California, where she set up a base in 2011.

Ex-Olympian Margarita Mamun, who won gold for Russia in rhythmic gymnastics in 2016, was among Efimova's supporters to enjoy the videos, saying: "Always wanted to see that live."

Russian pop star and producer Irina Nelson added: "Oh my god – how beautiful, Yuliya."

Bioluminscent tides can last for around a month, but Californians were unable to enjoy their latest local example of them while beaches were closed during the first weeks of the outbreak.

Health officials in California have been forced to issue specific guidance as huge numbers of people have since attempted to catch sight of the striking waves while stay-at-home orders continue across the state.