Tree house bottom floor?

Question:i have a tree house me and my firends want to add a bottom floor so we can fit every in my tree house so i have a top part so i want to put a hole at the bottom so we can climb down and have it ground level

Answers:
Get a sheet of plywood about 18mm thick, and cut it to suit. You may need some 100mm x 50mm as a sub-frame.