We wait outside the port of Natal where our mission began and where it will end.

11:40pm, March 30, onboard the Research Vessel SEWARD JOHNSON (RVSJ) -- The skyline of Natal, Brazil looms on the horizon, welcoming us back to where our expedition began. We will not be permitted to dock until morning, so we'll spend a night watching the cityscape from our floating home on the gentle seas. Conversation around the ship turns to the completed mission -- to lucky breaks and close calls -- to the sharks successfully sampled and the sharks that got away.

Chief Scientist Samuel Gruber considers the mission a success on many levels. "First, it was a success just getting down here with the highly restrictive permitting of the Brazilian government, the danger of the site, and equipment problems. Then, there was the recruiting of the crew, 29 Brazilians and Americans all told, and getting them to the ship. But, the greatest successes were my collaboration with Dr. Ricardo Rosa (the Brazilian zoologist featured in Dispatch 17) and earning the trust of Zelia (the lone resident and guardian of the Atol das Rocas preserve)."

Queen Zelia's trust did not come easily. When we first met the mysterious island lady, it was easy to imagine we would soon be leaving at gunpoint. But, in time, as Zelia observed our respect for her ecological haven and our dedication to the sharks, she came to trust us -- I would even venture to say that she came to like us.

"Our successes came not so much in capturing and marking the animals," Gruber continued. "The success came in learning what we could and couldn't do. Theory is one thing and practice is another. It was the most difficult shark collecting I've done in 30 years," he said, pausing, obviously picturing some of the tougher times in his head. "Nature really tied us up and beat us. But, we learned!"

Genetic samples gathered from young lemon sharks in Brazil will allow expedition scientists to make many important determinations about lemon shark breeding biology. The Brazil mission will play an important part in Dr. Gruber's larger research program, aimed at finding out exactly what it takes in the wild to grow a lemon shark from infancy to adulthood.

I am happy, and a bit surprized to have survived my first shark experiences without becoming a snack. That is the value of being constantly surrounded by more shark experts than sharks! To achieve our research goals, we intentionally violated every rule of shark avoidance: Don't swim with chum in the water. Don't enter the water in areas where sharks are known to live, especially at night. Don't aggravate or corner sharks. The list goes on. The fact that we encountered so many of the toothy predators and only came away with one bite among us (a minor bite, at that) is a testament to the experience, training, and skills of the science crew. The fact that we and our gear were able to live and work in such challenging and remote locations is a testament to peerless quality of the Research Vessel SEWARD JOHNSON, her captain, her engineers, and the rest of her crew. This expedition has been an adventure, and an education, that I will never forget. The scientists, the ships crew, myself, and everyone reading these dispatches has shared in the unpredicatble, exciting nature of field research. Sudden discoveries -- unanticipated breakdowns -- the power of improvisation -- the whims of the weather -- a million, ever-changing variables brought to heel by force of will and the will to learn. Here is the true glory that goes to scientific adventurers...that their daily inconveniences and snags fade into memory, but the knowledge they bring back will belong to all of us as long as we live.