"Show me your treasures, and I will show you mine," Gerda said to Erik,
after the first stop.

The boy shook his head. "I bought something useful," he said, "and I
shall send it to my father;" but even with coaxing he would not tell what
it was, until they were all ready to show their treasures to Lieutenant
Ekman. So all three of the children agreed to keep their souvenirs a
secret, and had great fun slipping off alone to buy them.

All day and all night, and all the next day, the boat steamed across the
open lakes, glided noiselessly into the quiet canals, or climbed slowly
step by step up the locks.

Toward night of the second day Birger suddenly announced, "This is Lake
Viken, and it is the highest lake on the way between the two ends of the
canal route. The captain says that it is more than three hundred feet
above the level of the sea."

"Have we seen the prettiest part of the route?" asked Gerda.

"Far from it," was the answer. "The best part of the canal is still
before us, at Trollhättan, although the next lake that we enter, Lake
Vener, is a lovely sheet of water. It is the largest lake in Sweden, and
I must visit one of the lighthouses."

"And I must call upon one of the trolls when we get to Trollhättan," said
Gerda, shaking her head with an air of importance.

"I shall walk up the locks," said Birger.