Don's diary: Shipshape with duck tape and toilet rolls

Week one
I board a plane to San José to join the German research vessel FS Sonne . With me will be 19 geophysicists and biologists from 11 countries. I depart the UK with high hopes. Unfortunately the name of the cruise, "Seduction", turns out to be an acronym for a prosaic geological process involving tectonic plates, rather than an indication of a month of Bacchanalian pleasure.

The geophysicists will spend their time making a detailed map of the sea floor off the west coast of Central America, while the biologists will deploy nets at between 200m and 1,200m to study the amazing animals inhabiting this virtually unknown world that accounts for more than 99 per cent of habitable space on Earth.

Sea-going scientific trips are conventionally called "cruises", which conjures up visions of swimming pools and cocktails, rather than visions of wading knee-deep in decaying fish. Also, as sea time is so expensive (up to £20,000 a day), the ship works 24 hours a day, often allowing little time for sleep. What spare time we do have is spent hanging over the rail watching dolphins and turtles, although the sun is so fierce that if you stand still for too long, your shoes weld to the deck.

Week two
There are distinct differences between ships run by various nationalities. American ships are technically superb and run with enthusiasm, while UK vessels specialise in make-do-and-mend and resemble public school. Aboard Sonne there are regulations for everything, from which bin to place your rubbish in depending on its composition, to how to place your spoon relative to the teacup to signify your state of satiation.

Our ordered life is disturbed by the news that the crew on another German research ship has gone on strike. Plans are afoot to replace German seamen on research vessels with cheaper sailors from Eastern Europe. Many of the current, highly trained, crew face redundancy. Their motto, " Billig ist nicht preiswert " (cheap is not value for money) seems apposite.

Week three
By about this time in a cruise you find out how thorough your preparation has been. Unanticipated needs inevitably arise and we continually make Heath-Robinson-like modifications to equipment worth many thousands of pounds using cardboard, Duck tape and old soup tins. In fact, the huge contribution made by old toilet rolls to field biology is not widely appreciated. A degree in biology helps, but not as much as an intimate knowledge of the Blue Peter annual. A T-shirt worn by an American colleague says it all: "When the going gets tough, the tough use Duck tape."

Undoubtedly the most significant change in ocean-going research over the past 25 years has been the advent of email. Previously when at sea you were cut off from the outside world. Today, however, sitting on a boat in the middle of the Pacific, my daughter emailed me her GCSE results from a cyber cafe in Tunisia.

Week four
After nearly four weeks at sea, we return to dry land for a brief holiday in Nicaragua. Our Costa Rican driver warns: "They steal your things, rape your women, then kill you." But he could not have been more wrong. Modern Nicaragua, land of a thousand fruits, cloud forests and volcanoes, is exciting yet peaceful, and even the stray dogs begging for food from the table are models of good behaviour. As the car swerves to avoid a panther, it is difficult to imagine a more interesting area than Central America for a biologist.

Ron Douglas is professor of visual science at City University.