"That's so—there is a boat!" exclaimed the older Bobbsey boy. "I wonder whose it can be?"
But they did not learn at once, for the next day, when they all went to the cave—including Mr. and Mrs. Bobbsey—the boat was not there.
"Somebody untied it and took it away," said Freddie, as he pointed out the rock to which he had made fast the rope.
"Are you sure you tied it tightly?" asked his father.
"Yep. I made the same kind of knot you showed me," and Freddie told how he had done it. Flossie, too, was sure her brother had fastened the boat properly.
"Well, then somebody's been here in the cave," said Bert. "Say, it's a big place, Daddy! Can't we get a lantern and see where it goes to back there," and he motioned to the dark part.
"Some time, maybe, but not now," said Mr. Bobbsey, who, with his wife, had walked along the island path to the cave while the children rode in the goat wagon. "I didn't know there was a cave on Blueberry Island. I don't believe many persons know it is here. But the boat might belong to some of the berry pickers, and they hunted for it until they found it."
"Did the blueberry pickers make the funny noise in the cave?" asked Flossie.
"I don't know," replied her father. "I don't hear any noise now. I presume it was only the wind."
Mr. Bobbsey and Bert, lighting matches, went a short way back into the cave, but they could see very little, and the children's father said they would look again some other day.