How to tighten a bolt in a circular hole

tools

I've assembled a set of swings, and am trying to tighten the nuts at the top. The trouble is that they are embedded deep inside a circular hole and I can't get to them with a regular spanner.

What kind of tool should I be using? I had a good look in my local hardware store and couldn't see anything useful.

Here's a (dreadful) diagram of what I mean.

enter image description here

Best Answer

You should get yourself a socket wrench (also known as a ratchet):

Socket set