Students can be sometimes be heard complaining of drowning in work, so imagine how these University of Essex biologists felt.
Lectures, held 18 metres under the sea in remote Indonesia for the first time, took place during the institution's annual field trip to the Wakatobi Marine National Park in Indonesia.
It was organised by the University School of Biological Sciences for its students.
The ground-breaking underwater marine biology lectures were the first of their kind, revolutionising the teaching, educational and learning experience during dives on tropical coral reef systems.
For the underwater lectures, Professor David Smith used specialised audio equipment so he could talk to students underwater, explaining exactly what they were seeing as they were seeing it.
This was a world away from usual underwater communication involving basic slates to write on and hand signals.
"It was a fantastic experience as I was able to use the power of observation like never before," explained Professor Smith.
"I have been on thousands of dives over the years but this was a totally new experience as I was able to explain to students exactly what they were seeing and inject more passion and feeling into the whole lecture.
It was very special and transformed the whole experience both for me and our students."
Using a special teaching grant, Professor Smith was able to buy an audio system which, to date, has never been used for formal lecturing and is only used by TV presenters and some professional divers.
Professor Smith wore a full face mask which included a microphone and the students wore headsets so they could hear him talk.
A hydrophone – an underwater microphone − was then positioned in the water which was linked to a control box and recorder on a boat.
Threats to the future of the world's coral reefs form the backbone of research being carried out by the university's Coral Reef Research Unit (CRRU).
It is examining the impact of climate change on coral reefs and how to work with nature to find a solution.
More than half a billion people depend on coral reefs for food and income.
Second-year marine and freshwater biology student Tilly James said: "It was an experience you simply cannot get with traditional lectures.
"Professor Smith was able to ask us questions throughout the dives, encouraging us as students to apply our theoretical knowledge in a much more practical setting."
