Adventurer Bear Grylls has dumped not one but two more batches of people on tropical islands to see if they can survive – with insufficient training.

“You could totally argue that. It is absolutely bare bones minimum,” he says at the launch of the second series of Channel 4’s The Island with Bear Grylls. 'The Islanders' – this time 14 men on one island, 14 women on another – get just two days of training. 

“It’s enough to teach them how not to hack their fingers off.” Fortunately, all 28 people did eventually make it back alive. “Just.”

It certainly makes for scary viewing: Grylls drops each group off at swimming distance from the rocky shore of their island and doesn’t return for six weeks. They’ve got to find shelter, food, and film the whole experience themselves (the camera crew also take part). The length of their stay is a secret even to the contestants, who vary from website designers to builders via hairdressers and potters. This second series is even tougher because it was filmed during rainy season.

But using 'regular' people, who have zero survival experience, is the purpose of the show, Grylls says.

“We don’t want to give people all of the knowledge. Then it becomes a survival programme and it’s not. It’s about what happens to humanity if everything’s stripped of you.

“We do purposely keep the training minimal,” Bear continued. “We want it to be experiential. You learn by mistakes. One of the key principles in survival is failure; you have got to fail. I said this to the guys in their training – get out there and fail. Don’t be scared of it. Don’t be scared of looking silly. Just keep trying. Then for me it’s interesting, then it’s an experiment, rather than show me some bush craft.”

It made it a tough watch for the survival expert, who says sitting on his hands was the hardest bit, especially when there were injuries. “I get nervous on this show because normally, if it’s Running Wild or Mission Survive, I have some control, I’m guiding. The difficult thing for me is watching. I’ve got 28 people who are total rookies. I’ve given them two days training, they’re dehydrated and beaten up and tired. You know what we’re all like when we’re tired; we make mistakes. And they’re waving machetes around. They’re exploring, climbing, wrestling snakes and crocs and stuff is going to happen.

“Stuff did happen and there were a few occasions where we had to get the medical team involved. On the whole it was remarkable what they achieved with so little injury”.

Even so, the show has been dogged by calls of fakery. The first series was criticised because additional animals including crocodiles were released on the island and a water source was secured. The same was done for this series. “I have a duty of care,” explained Grylls. “I can’t drop people on an island where there’s no water source and there’s no rain and expect them to survive. You’ve got to provide some sort of sustenance. We sort of build the ultimate island. So yes, there’s water, there’s food, but they’ve got to have the strength, the determination, the resourcefulness, hiking however many hours to hunt and find this water every day. It was hell on earth.”

Fakery wasn't the only complaint: the addition of a woman’s island comes after the first series came under fire for only recruiting male contestants.  

“We got all of these accusations that we were sexist because we hadn’t done a women’s version. When I read them at the time, I thought 'Good, that’s what we really want to do'. For season two it was logical.” Why not have a mixed island? Not until "around series eight", he says, laughing. 

Bear says watching the two groups approach the task in two very different ways was “shocking” and “revealing” in a way he hadn’t anticipated. At first they live up to stereotypes: all the men want to be Rambo and the women waste a fair amount of time standing around chatting.

He jokes that when he left the women, his first thought was “this is going to be messy” but "it settles a bit".

“But it’s not about gender; it’s about attitude," insists Grylls. "Some people crumble when the pressure goes on, when it’s been raining for four days: you’re tired, beat up, missing home. Some people get a glint in their eye. The hardship brings something primal out in them. You can’t call that. That’s not about being a man or a woman. That’s always inspiring.”

The Island with Bear Grylls starts on Wednesday 8th April with the men and Thursday 9th with the women, both at 9pm on Channel 4