This is level 42 of the Main tunnel.
You'll find that this level is a darker shade of orange than Level 41. It will get deeper and deeper until level 50.
Just avoid the holes, and always use the long jumps for the Runner. When the gaps are smaller, short, quick jumps are recommended. Since parts of the platforms are of crumbling tiles, be careful and don't panic. Just jump on the crumbling tiles.
For the Lizard, remember that if you stay near another platform, you can choose when you land. This can be very helpful and can boost your chances for finishing this level.