He tasted salmon that had been chewed on by a bear, but passed on drinking his own pee. Thus did President Barack Obama test his mettle in the wilds of Alaska.

Obama was the celebrity guest in an airing of "Running Wild with Bear Grylls," a reality TV shows in which famous people try out their survival skills in the great outdoors.

The presidential episode was taped in September but aired Thursday night.

For Obama it was an opportunity to press his case for protecting the environment -- and do so from a supremely pristine venue -- and speak outside the Oval Office.

The commander in chief alternated between serious talk on battling climate change and jokey banter on what he called "one of the best days of my presidency."

"For security reasons, I am not allowed to have a smartphone," Obama said before taking a selfie with the phone of one of his staffers. Obama said he anticipated some ribbing from his teenage daughters.

As they ventured into an area popular with bears, host Grylls warned the president that the animals are most dangerous when interrupted while mating.

"I think that's probably true for humans as well," Obama deadpanned.

A bit further on, he tasted the leftovers of a salmon that a bear had chowed on and left by a riverbed. Obama said it was good, but would be better with a cracker.

Then, this: in a pinch, would he be willing to drink his own urine?

"I suppose, in extremis, it's something that I would do -- if the alternative was death."

He added: "It's not something I'd make a habit of. And I probably wouldn't do it just for a TV show."

So what is the president of the United States afraid of? When his wife Michelle gets mad at him, she gives him a real mean look, Obama said. But no phobias, thank you.

After eating a marshmallow roasted on a camp fire, Obama spoke about the fight against global warming.

Gazing off at majestic glaciers, Obama said:

"I have two daughters, and I don't want grandkids too soon. But eventually I hope to have some. And I want to make sure that this is there for them, not just us," Obama said.

Obama spent three days in Alaska during this trip, which he took months before the Paris climate summit that ended last weekend with a global accord to cut greenhouse gas emissions.

His message in late summer on climate change was this: "We are not moving fast enough."