When it comes to protecting the environment and the critters who live in it, a group of Hunter people are trying to draw attention to the parts that aren't necessarily seen.
Combined Hunter Underwater Group, better known as CHUG, has been working hard to study and help protect the undersea environment in the region.
CHUG chairperson Margo Smith said the group formalised in 2012 as a way for scuba divers, snorklers and other interested people to raise awareness of the importance of the marine environment between Port Stephens and the Central Coast.
"The marine environment makes up over 70 per cent of the planet," Ms Smith said.
"It's not seen so it often doesn't have a voice - out of sight, out of mind.
"Our role is to fan the flame of knowledge."
The group has conducted a variety of oceanic projects including beach cleanups and debris surveys.
"We survey to find out what rubbish there is and where it's coming from then we remove it," Ms Smith said.
They also conduct regular animal surveys on fish and their longest running project - the sea slug census.
The group joined with Southern Cross University in 2013 to conduct a sea slug census at Port Stephens each season as well as an annual survey at Swansea.
"Sea slugs are fairly short lived," Ms Smith said.
"It can give us an idea of the changes in the marine environment - water temperature, what's growing under the water."
The surveys are held over a 48 hour period, when a diver will grab a buddy and a camera and document sea slugs and sea hares across the two days.
"Some very passionate divers even go out at night," Ms Smith said.
The census data has been used in various scientific papers and has spawned similar sea slug events elsewhere in the country.
The group's interest in other areas has also been used by various organisations and groups' for scientific research.
CHUG members man a spot at Redhead each June to count whales for the annual ORRCA census and information from the fish surveys has also been passed on to researchers to help them discover what fish can survive here and whether they can breed.
"It shows what citizen science programs can do," Ms Smith said.
"The information that's being collected isn't just sitting on someone's computer not being used.
"The volunteer divers are also acknowledged for their efforts.
"It gives them purpose knowing the time they've spent is being used and has proven valuable."
The group's next sea slug census will be held at Swansea on Saturday, December 12.