Hurrying to the cabin, Captain Henderson opened the side window shutters, turned off the electric lights and peered out.
"I can't see anything," he said. "Yet I should be able to, as we are not very deep."
The gage showed that the ship was submerged only thirty feet, and at that depth there should have been no difficulty in seeing, at least dimly, objects under water. But the windows showed as black as night.
"Bring me one of the portable searchlights," called Mr. Henderson.
Washington brought one, operated by a storage battery. Holding it so the reflector cast the beams out of the bull's-eye and into the water on the opposite side, the inventor peered forth.
"I was afraid of this!" he murmured.
"We are caught in the Sargasso Sea," replied Mr. Henderson.
"The Sargasso Sea?" repeated Mark, in a questioning tone. "What is that?"
"It is a great sea of grass," replied the captain. "An immense ocean of sea weed, that sometimes floats on the surface and sometimes a little below. The stalks or blades of the grass are very long and closely matted together."