Mattapoisett Recreation and the Marion Natural History Museum teamed up again this summer for the second annual Nature Explorers to teach students all about the watershed.

"Kids have been learning all week about how to keep the water clean," said Elizabeth Leidhold, who lead the program and also directs the museum.

Each day, Leidhold's young scientists experienced different areas of the watershed. On one morning, the group visited Bob Field's aquaculture farm. They also learned how to catch blue crabs near Reservation Beach.

Friday morning, kids got a tour of the harbor by Harbormaster Jill Simmons and Assistant Harbormaster Jim Sullivan.

"The water used to be a lot deeper here," said Simmons, explaining that whaling ships used to be built where now there is only seven to eight feet of water.

As they learned about saltmarshes, returned a box turtle to the wild and discovered importance of eel grass, the kids were taught an important lesson.

"It's important that we realize 'all drains lead to the ocean,'" said Leidhold, quoting a line from "Finding Nemo."

Many kids had so much fun last year that they returned to the camp this summer, including Thomas Keene and his brother, of Beverly.

"This year's been pretty fun," said Thomas.

Catching crabs was one of the highlights.

"I like crabbing," he said. "They're fast. It was great."

Leidhold said there were some aspects of the watershed that the group didn't have time to visit this year, and she would like to extend the camp to two weeks in the future.

If she does, many of her students plan to be there.

"I'm coming back to this camp next year!" said Kate Porter.