Step 1:

Start by sketching an arc/semi circle shape like in sample 1 below. *Then start to add triangular shapes for the fins and tail like in sample 2.

Step 2:

Once you have your general guide down you can start to add detail like below.

Step 3:

Once you’re happy with your dolphin lightly erase all unwanted marks and go over it again using a darker pencil or fine line pen like in sample 5. *Once this is done your ready for the fun part, shading!

Step 4:

I haven’t it shown it here but for extra effect try adding a few splashes of pencil marks below the dolphin.* This will give the impression that its jumping out of water.