They may be rivals in the sport arena but outside the competition many women athletes appear to be forging a sisterly bond.

Their interaction on social media reveals what the television cameras often do not capture: mutual encouragement and developing friendships - a true Olympic "sisterhood" that seems to go far beyond victories or defeats.

Female athletes from a wide array of sports and nationalities have been engaging with each other, even rooting for one another, and sharing hopes and aspirations.

Smiles from Biles

US star gymnast Simone Biles, already a three-time world champion and a media sensation, has been showing her sisterly solidarity with her roommate, who is not only her team mate but also her rival for individual gold.

"Behind the scenes: facemasks and head wraps," she recently wrote on Twitter alongside a picture of herself and Aly Raisman. (@Simone_Biles)

Raisman, the US gymnastics team captain, is a two-time Olympic champion who previously won gold in floor exercise, a discipline in which Biles is now wowing the globe.

Both of them have taken lots of group pictures with heart icons and flexed biceps emoticons, and are frequently seen hugging and smiling.

Raisman was predictably proud when the US won team gold on Wednesday.

Girl power - in twos, threes and fours

Tennis stars Serena and Venus Williams are just one of the pairs of female siblings competing in Rio, suggesting that girl power often runs in the family.

Tweeting from Rio, before she and her sister were defeated in the doubles tournament, a nostalgic Serena Williams offered a glimpse of her phenomenal career alongside her big sister Venus.

"Our first gold" read the title of an Instagram photo showcasing their big smiles on the podium in the 2000 Sydney Games.

Brazilian identical twins Bia and Branca Feres, who are competing together in synchronised swimming, like to share everything from their social media account to the pair of identical-looking white kittens they are seen cuddling in one of their Instagram posts.

But sisterly camaraderie does not stop at two.

Estonian marathon runners Liina, Leila and Lily Luik have been a social media hit with their special hashtag #TrioToRio.

They are the first triplets to qualify for the Olympics and they have been a favourite with fans who have joked about how race stewards will tell them apart.

They may not be sisters but Canada's 4x100 freestyle Olympic swimming relay team also decided to create a "sisterhood" by showing off their Olympic rings, given to them by Swimming Canada.

In smaller delegations, the feeling of camaraderie amongst female athletes has been even more marked.

East Timor has only sent three athletes to the Olympics, two of whom are women.

Anche Cabral will be competing in the mountain biking and Nelia Martins in the marathon.

The two have been busy posting pictures of the themselves making new friends in the Olympic village.

Below Cabral poses with two athletes from Ghana.

However big or small the delegation, judging by their posts on social media, they share a sense of excitement and achievement that binds the Olympic "sisterhood" together.

(BBC)