Saturday marks the first International Day of Climate Action, a grassroots protest spearheaded by environmentalist Bill McKibben and 350.org, an organization that gets its name from climate expert James Hansen's warning that atmospheric CO2 has to stay below 350 parts per million in order to prevent catastrophe. In honor of the event, thousands of campaigners in 172 countries are holding creative protests. It's hard to say whether the International Day of Climate Action will spur any real action from politicians at December's UN climate talks, but the protest ideas are inspiring nonetheless. Here are some of our favorites.

1. 350 Condoms Collage

The International Planned Parenthood Federation/Western Hemisphere Region is making this collage in New York City to remind people how important the fulfillment of sexual and reproductive health needs are in creating a sustainable and healthy world.

2. 350 Banner

Perhaps the most visible of tomorrow's events, this 350-foot banner was as the culmination of a 6-week long national art project. Stay tuned tomorrow as 100 people make a circle in front of the White House with the banner, which will be photographed from the air.

3. Splash Mob

A group of protestors in Norwich, U.K will meet at noon in Haymarket Square dressed up in swimwear--goggles, flippers, cardboard cut-out boats, etc.--to raise awareness of the potential sea level rise caused by climate change.

4. Underwater Relay

The Maldives is the lowest-lying country in the world. It's not surprising, then, that the island nation is putting on a number of protests tomorrow. This relay, a protest held by scuba divers and snorkelers holding hands underwater, hits home.

5. Human and Sandbag Seawall

Boston protestors will gather tomorrow in Christopher Columbus Park to form a human and sandbag seawall. Participants in the so-called Boston Under Water Festival will come dressed goggles, snorkels and life vests.

6. Bathe-In

Hundreds of Hungarian bathers will jump into Budapest's public baths and do a synchronized swimming performance.

Know of any other creative Day of Action protests? Let us know in the comments.

[350.org]