A climbing apparatus includes a mast having a plurality of mast segments operable to vertically stack one after another. Each segment includes a stand-off to abut against a climbing object and form a space for receiving a strap to secure the mast to the climbing object. The apparatus includes a platform assembly having a (i) a platform, (ii) a seat spaced apart from the platform, and (iii) a frame connecting the seat to the platform. An upper trolley is provided for independent mobility up and down along the mast. The upper trolley includes a first brake connected to a handle operable to actuate movement of the trolley. A lower trolley is provided and is operable for independent mobility up and down along the mast relative to the upper trolley. The lower trolley includes a second brake and is connected to the frame of the platform assembly.