A vacation spent taking urine samples from a crocodile doesn't sound like everyone's idea of a good time, but for accountant Derek Stapley it was the ideal way to relax.

Now Mr. Stapley will be sharing those experiences when he gives a lecture about volunteering with crocodiles on the Botswana Okavango Delta, at the Bermuda Underwater Exploration Institute (BUEI) tonight at 7 p.m.

"I am certainly not an expert on crocodiles," said Mr. Stapley, who works as an accountant for Ernst & Young, when he isn't getting crocodiles to aim into a test tube.

After going on a couple of safaris to Africa, he decided he wanted a more hands-on experience with some of the world's most endangered creatures.

Four months ago he volunteered with Earthwatch, a charity that sends people to help with environmental research all over the world.

"I chose crocodiles because they are fascinating animals," said Mr. Stapley. "They are some of the oldest surviving animals we have ever known.

"They are very effective hunters. They have survived for millions of years and are very different from other animals in terms of catching them, watching them and photographing them."

In order to catch them, Mr. Stapley had to go out at night with researchers in a 25 ft aluminium boat.

"We would find the crocodiles by shining very powerful search lights on the edges of papyrus reeds along the banks of the Zambezi river. Their eyes reflect back red. The crocodile stays in position like a deer caught in a headlight. You gun the boat, move in and then work out what size crocodile it is."

The average size of a Nile crocodile is 16 ft, but they can grow to as much as 20 ft and weigh up to 1,650 lbs.

Scientists are concerned that with global temperatures on the rise, Nile crocodiles may have a harder time finding a mate.

"After we located a crocodile, we would bring them on board either by hand-catching one behind the neck, or by using a noose," he said. "Then you would go through a number of steps of processing the crocodile. We would take blood samples and urine samples, weigh it and measure it."

Naturally, to take a urine sample from a crocodile requires the assistance of more than one person.

"One person holds the crocodile up so his body is facing outward. He has an opening called a 'cloaca' used for sex and peeing. The crocodile is fairly scared so it will often urinate itself. If not, there are number of things you can do to help it urinate and you can catch the urine in a little test tube."

Volunteers also cut a scoot out of the tail to create a unique identification mark or attached a tag.

"The last stage was pumping out the stomach of the crocodile, which is fairly unpleasant for the crocodile. You end up with a large pile of mush. We had to take that back to be processed in the lab. After that you had to get the crocodile as quickly as you could back into the water."

He said scientists have studied whether the crocodile suffers any long-term stress from this alien-abduction-like experience, and found that it doesn't.

He said that the endangered Nile crocodile is a vital part of the eco-system in the Okavango Delta. His volunteer efforts helped scientists to work out the number of crocodiles in the area, their diet and the reproduction cycle.

"The longer term goal and objective is to implement a conservation policy for the long-term survival of the crocodile," he said. "They are being extremely successful in doing so, which is great."

The programme is also examining animal-human conflict in the area. The crocodiles are quite dangerous to other living things near the river, including humans.

"The problem is that crocodiles take a lot of younger and older people," said Mr. Stapley. "They also take domestic animals. Most of this happens on the edge of river banks. People go down to river to wash their clothes or themselves, or people go swimming. Adults are sometimes taken out of open kayaks. Hopefully, by doing research like this there will be a better understanding of the times of the year when humans are more vulnerable."

Although they are dangerous, predators like crocodiles are actually very important to the eco-system. "The crocodiles will eat the fish that are there," said Mr. Stapley. "If the cat fish population was to get out of control, for example, that would have a negative effect on other animals. The crocodile is on top of the food chain. It acts as a very good control of animals beneath it in the food chain."

Mr. Stapley and other team members also set traps for larger crocodiles and helped to monitor nesting sites.

This was not Mr. Stapley's first Earthwatch project. A few months before this one, he worked with lions. "That will be the subject of a separate presentation, and I hope to do one with hyenas this summer," he said.

Earthwatch requires that volunteers pay for their flight, accommodation, food and other expenses. Many people are sponsored to take part by their company, but other people without sponsors can pay several thousand dollars to take part. It also encourages its volunteers to do some kind of positive project to help the environment in their own countries.

"I would like to encourage other people to take part in Earthwatch programmes," said Mr. Stapley. "There are an incredible range of projects and programmes. There is literally something in there to suit everyone from archeological digs to working with dolphins to catching crocodiles and hyenas.

"It is just a fantastic experience. You are part of a team of volunteers from around the world working with some of the top scientists in the field. The reason the scientists need volunteers is because of costs. They can afford to put two or three scientists in, but projects need teams of six, seven or eight people to carry out the work, whatever it is."

He also said it was a great opportunity for amateur photographers like himself.

"On safari do you rarely get that close to animals and get the chance to photograph them close-up," he said.

Proceeds from the lecture night will go to the ISIS Katmandu Kids Club charity.

Tickets to the lecture are $15 for BUEI members and $20 for non-members. Telephone 297-7314 to purchase tickets. Doors open at 6:30pm (cash bar) for 7pm start. Dinner tickets are $33.75 .

For more information on Earthwatch check out www.earthwatch.org.