The peace prize -- the highlight of the Nobel season and the only one of the six Nobels awarded in Oslo -- always sparks wild guessing games, rendered especially tricky by the fact that the list of nominees is kept secret for at least 50 years.

Only their number is known: this year there are 318 nominees, including 211 individuals and 107 organisations, according to the Nobel Institute.

That leaves much to the imagination of experts.

"In the absence of a very clear front-runner... I think that we could and should see a prize to either an umbrella organisation for journalists or individual journalists working in the field," suggested Henrik Urdal, the director of the Peace Research Institute of Oslo.

"During conflicts, it's extremely important that journalists contribute to provide information about what's happening, both in order to hold the conflict parties accountable for their actions as well as providing information to the outside world that allows governments an opportunity to assess the situation and possible measures," he explained.

Both Reporters Without Borders, known by its French acronym RSF, and the US-based Committee to Protect Journalists have been mentioned as possibilities.

Teenage climate activist Greta Thunberg is also a name on experts' lips, either alone or with other activists.

She was favourite to win the prize last year, when it went to Ethiopian Prime Minister Abiy Ahmed for helping to end a 20-year postwar stalemate with Eritrea.

Nobel historian Asle Sveen said that while RSF was his first choice, Greta, as she is simply known, was "a possible candidate, absolutely".

Greta would be the second-youngest laureate in the Nobel Prizes' almost 120-year history, after the Pakistani advocate for girls' education Malala Yousafzai.

"Even if you have this pandemic right now, climate change is in the long term much more serious," Sveen noted.

- No Nobel for Trump -

Meanwhile, the new coronavirus pandemic has pushed the World Health Organisation (WHO) to the top of online betting sites, just ahead of Greta.

That would be a way for the five-member Norwegian Nobel Committee to honour the UN agency's multilateral approach to the virus.

But the WHO has also been sharply criticised for its slow response, while Donald Trump has accused it of yielding to Chinese influence.

It's also not known whether the WHO was nominated in time. The new coronavirus was defined as a pandemic on March 11 -- while the deadline for peace prize nominations was January 31, and Nobel committee members can only add their own suggestions at their first meeting of the year in February.

Other names making the rounds in Oslo include German non-governmental organisation Transparency International, the World Food Programme (WFP), the UN and its secretary general Antonio Guterres, German Chancellor Angela Merkel and Afghan politician and women's rights activist Fawzia Koofi.

Those eligible to nominate candidates for the prize are also allowed to disclose their choice.

As a result, those believed to be on the list include the people of Hong Kong, NATO, indigenous Brazilian leader and environmentalist Raoni Metuktire, the whistleblower trio of Julian Assange, Edward Snowden and Chelsea Manning, as well as Greece's ex-prime minister Alexis Tsipras and his Macedonian counterpart Zoran Zaev.

Whoever wins, Covid-19 will impact the prize this year.

Depending on the corona restrictions in place at the time, it will be awarded on December 10 either in-person at a scaled-back ceremony in Oslo, or remotely in an online ceremony.

While Trump has been nominated by two Scandinavian MPs, it is not known whether he is a candidate this year.

Trump seems to revel in the idea of being a Nobel laureate, given the number of tweets he has written about the possibility.

But experts don't think that will happen.

"Trump is more likely to get the Nobel prize in literature for his tweets than to get the Nobel Peace Prize," said Urdal.

"And that's not because he is Donald Trump, that's because he hasn't done anything that is deserving of the prize."