Last year's cast faced challenges including navigating in a rally car, serving in a restaurant and singing the National Anthem. It wasn't always easy but they all made it through. This is what three of them thought about the experience:
DEREK BROCKWAY, Weatherman
I'm really glad I took part in The Big Welsh Challenge. It was fun to do and it also inspired me to take up learning Welsh again. I'd done O-level in school - and the programme brought it all back to me. I've started learning now with a friend.
It's been really useful for work too - I've done interviews for the Welsh language TV news programme, Newyddion, and the children's news programme, Ffeil. I also speak Welsh to people in the office more than I did before. The Big Welsh Challenge has helped me gain confidence and I intend to continue learning.
The language is very much a part of our heritage and culture and it's nice to feel part of all that. I love the Welsh place names I put on the weather map - there are some really great ones out there. It's good now that I know what some of them mean.
SUZANNE PACKER, Actor
I really enjoyed taking part in the last series of The Big Welsh Challenge - except for the task where we had to serve in a restaurant speaking to the customers in Welsh which was a bit like trying to tap your head while rubbing your stomach! It was very tough and came early on in the series when I hadn't had much chance to learn anything.
I speak Welsh when I can. My son is in a Welsh medium school and he comes home with books to read so I try to keep up with the vocabulary. I also speak to other learners or Welsh speaking parents at the school gates but I can't have a fluent conversation yet. I have occasional lessons too and I use the BBC Catchphrase CDs in the car on the way to work.
My aim is now to build on what I know and make sure I improve and don't lose the language. I think when you send a child to Welsh medium school it means you're prepared to take an active role in the learning process and I know for me that will become more of a challenge as he gets older.
STEVE MEO, Actor
For me the programme was a stepping stone. I could already exchange pleasantries in Welsh but The Big Welsh Challenge gave me the impetus to try out more. I had a good time doing it. It showed me that there's not such a mountain to climb to learn a language and once I started it was almost addictive.
I've used my Welsh quite a bit socially since taking part but the biggest problem is that I live in London most of the time and I haven't been home to Ystradgynlais much recently. Most of my acting friends in Wales are Welsh speakers so if I go out with them I get the chance to practise. I haven't lost as much as I thought I would from being away.
I've got a little nephew now who's starting to come out with words like "bwyd" and the names of farmyard animals. It would be nice to think one day I'll be able to speak to him in Welsh.