The reason the Leafy Seadragon seems so elusive is that it blends so well into its environment.
It does not matter if it's in kelp or bubble weed or any other of the many species of yellow algae inhabiting our coastal waters, they just seems to disappear into the detail.
For many years I dived in locations where Leafy Seadragons were common and never saw them until I started photographing them.
Now I see them most times I dive where they are still hidden most of the time but not so elusive.
Photo: Robert Rath, 'Crouching Diver, Hidden Dragon', 1/200s f/5.6 ISO200 15mm