There are some TV programmes that leave you open-mouthed.
Jaw-droppingly impressive, they have you glued to your seat, staring in wonderment at what you've just witnessed on the small screen.
And, after watching Swimming With Crocodiles (BBC Two Wales, Sunday, 9pm) that's how I felt, although I never want to set foot in seawater again.
The documentary took adventurer Ben Fogle to Australia's Northern territory to research saltwater crocodiles.
And for Ben and his team of experts and researchers, that meant physically getting in the water with these man-killing machines.
There was no need to question whether he was stark raving mad - he was the first to admit that it was the most terrifying thing he'd ever planned to do - and from a man who has rowed 2,931 miles across the Atlantic, run the Marathon des Sables in the Sahara Desert and even trekked to the South Pole, that's saying something.
He was visibly shaken when he watched a 6ft crocodile stalking the water while he sat in a very exposed boat before jumping out to try to catch some meat.
And he was even more terrified when he helped a park ranger teach a naughty croc a lesson.
Watching a burly statuesque man sitting astride a crocodile to 'educate' him was certainly a first for me.
What the film aimed to do was try to find out exactly what goes on under the water and it certainly succeeded.
At the surface they can kill humans quickly and efficiently, but when they are swimming deep below, they were completely at ease with the divers, ignoring Ben and the team as they swam a safe distance away with only a pointy stick to defend themselves.
It was enthralling telly but Ben must be breathing a sigh of relief to be back on dry land.
I was also impressed with former Pop Idol runner-up Gareth Gates as the one-time stammerer helped other people who wanted to get rid of their speech impediment (Stop My Stutter, BBC Three, Monday, 9pm).
In a moving documentary, Gates helped other stammerers as a tutor on the McGuire programme, which helped him get rid of his speech impediment almost a decade ago.
During an intense four-day course, he showed his clear passion to help others, including Sarah Webster, who dreamed of becoming a teacher, and Simon Robinson, whose condition was so bad he could hardly say his name.
It was difficult to believe that just four days would cure them but with Gates' enthusiasm and a host of lessons in breathing and confidence, there was a marked development for all them.
Watching them give a speech at the end of the course was very moving.
More than 600,000 people stammer in Britain and although the documentary didn't go into the reasons for this, it was nevertheless interesting to see how a once shy 17-year-old had blossomed into a confident speaker, and an obviously inspirational figure for so many people.
And while Take Me Out (ITV1 Wales, Saturday, 8.05pm) could never be labelled as educational or awe-inspiring, it's hilarious.
I wasn't a fan of the series at the start but Paddy McGuinness, with his cheesy catch phrases and his merry band of women looking for love, certainly kept me amused on a quiet Saturday night in.