Recently while off on the boat I realized I had done just that. I had forgot to bring a a sketchbook or a pencil. In this case I found a scratch pad I had aboard that I had previously made from quartering sheets of unwanted printer paper and stapling them together. Fortunately I also found an ink pen stashed away in a drawer.
Below you'll see the gorgeous sunset we saw while we were on the boat as well a a couple of sketches.
Looking west as we sat in the cockpit enjoying a glass of wine.
I sketched these shell pieces i found while on the beach and the one below was a sketch I did from down inside the cabin looking out.
Neither are anything special, but represent the fact that if I really feel like sketching, not having my sketchbook along isn't a good excuse.