There are several types of rope ladders that can be made. I remember using one as a kid, that someone set up to climb a tree overhanging a lake, with another rope tied further out on a branch to be swung from out and over the water.
I've seen some use flat wood planks or round pole sections, others may just be knots spaced along a length of rope.
Not everyone can manage climbing a knotted length of rope, but having rungs makes a rope ladder easier to 'navigate' for most. This type of ladder also makes it easier to get back into a boat from the water and has also been called a 'knotted bathing ladder'.
I chose to make this simple one that can be found in various knot books, including 'The Morrow Guide to Knots'. A good online link, with an animated diagram for this type of rope ladder, can be found at Marinews.com. This type of ladder is easy to make and also easily taken apart if you need the rope for something else.
I used a 50 foot length of 3/8" sized 'high strength' rope for this ladder that ended up at about 9 feet long overall. There are 7 rungs set about 14 inches apart and just wide enough for hand/footholds.
It's up to you to choose the amount and type of rope, the width of the coiled rungs, and the distance between them and that will determine the final length of a finished ladder. For safety's sake, know the strength of your rope, don't guess, and use at your own risk.
These instructions will make more sense if you follow the animated diagram. You start off at the center of your length of rope. I made a figure 8 knot with the rope, but other instructions may start it off differently.
You come down with one length for the first rung and make two bends. Take the other length of rope and run it through the first bend, then under the next, and start tightly coiling that rope around both bends. When you have the rung length that you want, run the cord through the loop end of the other bend.
At this point, things are still loose enough to adjust and even out the rope from the center point to the rung, if needed, tighten up and work any slack out of the coiled section, pull the rope on both ends to finish tightening and go on to making the next rung, alternating the bend/coil rope sections as you go.
The top section/loop of the ladder can be secured to a fixed object for climbing or attached to another separate length of rope, which can be thrown up over a branch on a tree or other fixed object, and then secured for climbing.
A final photo showing the rope ladder hanging from the second floor railing. It looks a bit uneven because the rope came from a tightly coiled package and still wants to revert back to that shape. Pulling with a little weight on the bottom made it look straight and even, but stepping back for the photo with just a walking cane hanging from it and it still looks uneven. I don't want to adjust it while it's still 'springy'.
And no, I ain't gonna test it from the railing. That would fall into the 'famous last words' category of 'Hey ya'll, watch this!', and would not end well for me or the railing, lol.
On a side note, I wonder if they still have climbing ropes in school gymnasiums?