For Becky’s ‘UP’ square, today, I’m featuring two views of the Undala lava tubes of Queensland; outside and inside the tubes.
The longest lava tubes in the world, they are formed (to give a lay explanation) when a huge mass of lava is on the move, but cooling as it runs. Subsequent lava flows add to it and run up the sides, eventually closing over the top to form a tube.
The last eruption was about 200 000 years ago.
Not so far from Cairns, they are well worth the visit.
Underdown 
Wow!
Looks wonderful indeed 🙂
LikeLiked by 1 person
Gotta love those lava tubes, the bigger the better as far as I’m concerned. The smaller ones make me squeamish!
LikeLike
Yes, the guides frequent mention of the potential instability of the ceiling /roof wasn’t easily brushed aside as unlikely.
LikeLike
Thanks, Jo.
LikeLike
Great word! 🙂 🙂
LikeLiked by 1 person
You are so right! I feel very privileged to be able to see so much of it in person.
LikeLike
how extraordinary, what an experience to walk through
LikeLiked by 1 person
It is. And yet, very hard to get your head around.
LikeLiked by 1 person
our planet is so extraordinary
LikeLike