The inaccessible location of the mountain meant that only very determined climbers ever reached the summit.

The top of the mountain was inaccessible to any type of vehicle. The vault was inaccessible to a casual visitor.

The summit of the peak appeared to be inaccessible to the weary mountaineers.
The kitchen area is inaccessible to the prison's inmates.

The suffix of the word "inaccessible" is "-ible."

The treasure was hidden in an inaccessible cave deep in the mountains, making it difficult for anyone to reach.