Skipping over the shallow waters of Limmen Bight in their patrol boat, the Marranbala rangers spot a saltie sunning itself on the banks.A bird stands nearby, in what looks like a perilous position."He'll clean his teeth for him," one of the rangers says.Saltwater crocodiles are among the diverse wildlife visitors to Limmen Bight are able to see. (ABC News: James Elton)Nearby, some commercial mud crabbers work their way along mangrove-lined banks, while recreational fishers motor deeper into the river system.Even above the water, it's clear Limmen Bight — located east of Katherine on the Gulf of Carpentaria — is a thriving, rich ecosystem.But underwater cameras deployed by the rangers, in partnership with university researchers, have now captured more than 100 hours of footage that reveals what lies beneath.David Barrett says there is potential for more tourism opportunities at Limmen Bight if the roads are upgraded. (ABC News: James Elton)"We had some great footage of sharks," lead Marranbala ranger David Barrett says."[We can see] the different seagrass species, but also different corals, soft corals."We were able to look at the fish stocks, which was really cool."While they eluded the cameras in the recent study, the seagrass is also home to one of the biggest populations of dugongs in the world.Ranger Emmalou Barrett says there have been times there were so many dugongs and turtles in the water, she had to "go slow and be careful" to avoid hitting them with her boat."It was amazing to see that amount," she says.Long-promised extensionThere are already two marine parks at Limmen — one run by the Northern Territory, the other by the Commonwealth.The NT government is proposing to extend its portion south, which would create a continuous protected corridor.At the 2024 NT election, the Country Liberal Party accused the previous Labor government of "dithering" on marine parks and promised to proceed with the extension, which would add some 185 square kilometres to the park, including a vast seagrass meadow.The Limmen Bight Marine Park is located on the shores of the Gulf of Carpentaria, south of the mouth of the Roper River. The NT government is proposing to extend its section south. (ABC News: Jessica Henderson)That seagrass is what makes the area so special."It's food for dugong, turtles, but it's also good for fish, prawns, mud crabs," Mr Barrett says."It's really important."NT Environment Minister Marie-Clare Boothby told the ABC an announcement on the extension was now "imminent", following public consultation that wrapped up in April.Fishing meccaThe fishing camp at Limmen Bight is a paradise for fishers from all over Australia, who often set up there for weeks or months at a time.Territory fisherman Ben Rosevear is one of them and says there's a unique "camaraderie around the camp" here."No one's going a million miles an hour," he says.Ben Rosevear says it's "not very difficult" to catch "12 species in a day" at Limmen Bight. (ABC News: James Elton)"You'll wake up and have a nice breakfast to chat to your neighbour and then get your boat ready and go fishing for the day."Standing on a sandy bank, Mr Rosevear hooks up some live mullet as bait.Within minutes, he's reeling in a giant queenfish."That's Limmen Bight for you," he says."To me, it's one of the most alive places in the Territory."You can see how clean and pristine it is, and you know, we want to keep it that way."To go out and catch 12 species in a day is not very difficult."The NT government says there is untapped potential in the area's recreational fishing market.The park is a mecca for recreational fishers from across the NT and the rest of Australia. (ABC News: James Elton)While in opposition, now-Treasurer Bill Yan said the extension of the marine park would help put the Territory's wild coastlines on "every fisher's bucket list".Ranger David Barrett agrees there is potential for more tourism, but says the access road is bumpy and requires a high-clearance four-wheel drive."The area can handle it, [but] the roads will need to be upgraded," he says.Mr Rosevear says he wants to see tourism in Limmen extend beyond fishing, to attract visitors who may not own a boat.Ben Rosevear says Limmen Bight is "one of the most alive places in the Territory". (ABC News: James Elton)"I think there's an enormous opportunity for wildlife tours, birdwatching tours, even sunset tours," he says.A tale of two parksThe topic of commercial fishing in the park is more controversial.The existing NT marine park allows prawn trawling in its outer waters, while the same fishing method is banned in the Commonwealth park right next door.Commercial mud crabbers also operate in and around the NT park.Mr Rosevear says he sees commercial fishing and marine parks as "inherently distinct" and allowing it risks making Limmen a "Clayton's marine park".But he says restricting operators to "handlines" only could be a starting point.Commercial mud crabbers operate in and around Limmen Bight, but there are different rules for different areas. (ABC News: James Elton)Keep Top End Coasts Healthy ocean conservationist Adele Pedder says the rules should be the same across both parks."A lot of people would find it surprising to hear that damaging fishing practices like sea floor trawling and gill netting is still allowed in the marine park," she says."It absolutely makes sense to standardise the protection across those two areas and make sure we protect the habitats in both areas."Mr Barrett says he'd like to see some temporary, seasonal closures of the crab fishery to "give them a chance to recover", similar to those in the barramundi fishery.Funding questions and the next marine parkThe work on the extension at Limmen Bight and the establishment of the Marranbala Sea Rangers has been supported by $2.27 million in federal government funding, granted to the NT.A federal government spokesperson said a 10-year deal had recently been inked with the sea rangers that would see them carry out patrols across both the NT and federal parks.Jacinta Hammer, another of the Marranbala rangers, said the job involved "hard work" and early mornings.David Barrett says there should be seasonal closures of the Limmen Bight crab fishery to "give them a chance to recover". (ABC News: James Elton)But she said community members from Borroloola, Ngukurr, Numbulwar and Minyerri had expressed interest in joining the group."Lots of family asked to come out and join us," Ms Hammer said.The federal government spokesperson said the "integrated management" approach at Limmen, using Aboriginal rangers to patrol across state and federal borders, could be a model for future marine parks.The NT currently has two marine parks — one at Limmen, and the other on the Cobourg Peninsula.Under its 10-year deal with the federal government, the NT has also produced a report for the Commonwealth on "multiple potential areas" for a third marine park, beyond the Limmen extension.A spokesperson for the NT parks and wildlife minister, Marie-Clare Boothby, said the establishment of the next protected area would require "further investigation" and "comprehensive consultation".