As the name suggests, you must go into the sink to find this geocache! Honestly, we thought that going down was harder than coming back out again.
It's an amazing feeling to be at the bottom, looking up at the walls surrounding you. In this picture, you can see the younger member of our team at the bottom:
Can you see him? He's that dark speck. That will be you as you search for the cache!
Obviously, the terrain on this one is going to be more difficult, so please be careful. Take caution because there are lots of loose rocks and prickly things.
We hope you enjoy finding this cache as much as we enjoyed hiding it! 
One more thing: If anyone knows the name of this particular sink, we would love to know!