Locating, detecting and making safe unexploded bombs is one of the most dangerous jobs in the world.
At the Defence EOD, Munitions and Search Training Regiment or DEMS in Oxfordshire, they train all three services for this vital role.
Currently on the final week of their Elementary Underwater Explosive Ordinance Disposal course, Royal Navy divers are learning where to place explosives to clear mines.
Leading Diver Ed Maddy said about the course:
“The students have been coming in and practicing what we would call a diver place charge drill.
“The charge has to be put in a particular place because in a buoyant mine, the majority of the charge is at the bottom, so we need to get our charge next to that to get the mine to function.”
AB Euan Wallace, a student at the diving school, told us about its challenges:
“Sometimes you can't really see anything in front of you. It's a lot of relying on your touch and senses. Stuff floats in really awkward places underwater.
“It gets cold quickly, so if you're not wearing the right sort of kit it can get really cold down there.
“You stop being able to use your hands as much as you'd like to.”
Euan began his Navy service as a chef but he's looking for a new adventure as a mine clearance diver, and so is AB David Kerrigan:
“Well, initially I was in the Army for 9 years. I got out, worked away for a bit.
“I wanted to join back up because I missed service life. And literally, the only thing I wanted to do in the Navy is clearance diving.
“It’s the one that you know is more exciting, you get to do more things that I find interesting.”
The two World Wars saw the biggest period of maritime mining in history.
It's estimated more than half a million sea mines were laid during the Second World War alone.
Add to that the amount of unexploded ordinance which ended up in the sea, and there are millions of dangerous items that shouldn't be there.
It’s a legacy that still leaves work for the Royal Navy. Last year Southern Diving Unit Two removed five tonnes of explosives from the seabed in just 12 months.
That included removing ordinance from the path of the new HMS Queen Elizabeth in Portsmouth.
But not all of the Royal Navy training happens underwater.
There’s something called the 'softly softly' process, which simulates diving at deep depths or in murky waters.
When these divers can't even see their hand in front of their face, they still need to be able to identify a piece of ordinance. AB Jamie Trickett told us about the process:
“I know that my arm length is roughly 67 and a half inches so I know that measurement and then I can add what's on my elbow to my middle finger.
“If I'm still not getting the measurement that I want I can still add this little crevice here on my finger to the finger tip, that's about an inch.
“You know there's about 5 or 6 different ways you can do it.”
Much of the learning also takes place in the classroom, where trainees are marked on just how accurate their drawing and recording skills are.
It's crucial because for their final test – and for real in their new career, when they'll do their identification underwater.