Royal Marine commandos have long been regarded as an elite fighting force.
Thirty-two weeks of stern training usually weeds out any fantasists and fainthearts foolish enough to apply.
An elite, maybe, but mythical supermen, no. That is a misconception the Marines want to dispel - one scarcely helped by a recent poster campaign adorned with the slogan: "99.99 per cent need not apply." Soon to be scrapped, this macho own goal has exasperated men on the ground whose job is to attract new blood.
They are keen to embrace all sorts. Many of the qualities for which they are looking are commonly found in college students on public-services courses. Such students have an appreciation of discipline and a structured life.
That is not so for some who arrive at the Marines' headquarters in Lympstone, near Exeter, to undergo a Potential Royal Marines Course lasting two-and-a-half days. What seemed a good idea in the careers office can come as a severe shock.
It is in everyone's interests if they know what to expect. Over the past two years, the Marines have encouraged would-be wearers of the green beret to sample the training routine at Lympstone. Their week-long Look at Life programme is a real and vigorous introduction.
Sergeant Steve Wright is a member of the Marines' visibility team. Part of his job is raising awareness of what the commandos are about. The opportunity to sample the life for real has grown increasingly popular.
"We do get repeat visits," he says. "Students want to come again when they've been once. Those on public-services courses can be ideal candidates - many are up to the fitness standards. One difficulty is the cultural change, but if they've been on a course, they're half way there."
Sergeant Wright, 40, became a Marine at 16. Most of his intake were the same age, but he doesn't recommend joining up so young. "Finish your A-levels or other qualifications first," he says.
On a windswept field, where BTec public-services students from Tamworth college tackle team-building exercises, Sergeant Ian Roy tells them to behave like "thinking soldiers".
"The Army is one thing; the Marines is another," he says.
Team-building - putting up a tent, retrieving fuel cans from an "electrified" compound and guiding an unsighted colleague through a minefield - is the second instalment of a gruelling day that begins at 8.30am with the swimming test.
Recruits in battle dress and carrying a rifle jump from an 8ft diving board, swim a length, and, while still in the pool, must hand over their weapons and extricate themselves from their gear.
Concessions are made to weaker swimmers but instructor Corporal Bart Ledger does not give up easily. A drama unfolds as one participant freezes on the diving board. His agony lasts 15 minutes before he slides into the water, and the corporal is satisfied. While the ability to swim is not an entry requirement, a non-swimmer recruit starts learning at once and takes the test within 15 weeks.
After team-building, students are shown the Marines' weaponry: the bayonet ("it has blood channels, it doesn't create a vacuum and is easier to pull out") and an anti-tank gun "that will turn the occupants into soup".
At lunchtime the students seem eager for more, which is as well because the assault course awaits them. A stiff breeze whips off the River Exe as everyone attacks the course with gusto.
Luke Deeley, 17, mulled over a career in the marines for some time. "This is the point where you can make up your mind, and coming down here has pretty well done that," he says. "For the rest of the year, I can aim for what I want, knowing what they will expect."
Captain Phil Robinson, soon to take charge of officer selection at Lympstone, sees the Look at Life initiative as a way forward. "There's been poor co-ordination and dislocation between the recruitment office and our base, although we are now trying to get better links," he says.
"There's a need for something between the careers office and people turning up for the Potential Royal Marines Course.
"We'll start doing things so they can come down here for a day or two and see what's expected. Hopefully, they'll then be better prepared."
Contact the marines on firstname.lastname@example.org