Look out past the heavy industrial skyline of Port Kembla, and your eyes will immediately land on the dramatic silhouettes of the Five Islands. For thousands of Illawarra locals, these offshore outcrops are a daily landmark seen from kitchen windows, coastal commutes, and headland lookouts. But beyond their scenic value, the islands host a hidden, highly complex marine sanctuary that is actively reshaping our understanding of coastal science.
On the latest episode of the Current Conversations Podcast, host Kurtis Ocean paddled out for a deep-dive conversation with Professor Sarah Hamylton. As an internationally recognised coastal geographer, Director of the Spatial Analysis Laboratory at the University of Wollongong, President of the Australian Coral Reef Society, and author of Plotting the Oceans: Stories of Powerful Maps and Their Makers, Sarah brings world-class expertise right to our local coastline. From satellite reef mapping in Fiji to drone-tracking the seal colony on Martin Island, Sarah pulls back the curtain on the technology, history, and ecology defining the South Coast.
The 'Bachelor Pad' of Martin Island
While the Five Islands appear as a single offshore cluster from afar, the archipelago is geographically distinct. To the north sit Bass Islet and Flinders Islet, while three lower landforms extend outward from the base of Hill 60 in Port Kembla. This lower trio includes a tiny rock platform that submerges at high tide, Big Island (joined in the middle by a low, rocky isthmus), and Martin Island, which faces directly out into the open Pacific Ocean.
It is on the flat, raised rock platforms along the southern edge of Martin Island that the local seal population hangs out. This rocky sanctuary is affectionately known to researchers as the "Bachelor Pad".
The colony is comprised almost entirely of male Australian fur seals, alongside occasional New Zealand fur seals. Because Martin Island serves strictly as a "haul-out site"—a location where seals gather to rest and recover between oceanic feeding runs—you won't find female seals or newborn pups here. The nearest major breeding colony is located further south at Barunguba (Montague Island) off Narooma.
Despite lacking arms or legs, these massive, blubbery mammals manage to haul their heavy bodies eight to nine feet up onto the exposed, flat rock shelves above the breaking surf.
Recommended Local Spot: You don't need a research vessel to spot local fur seals. Take a walk along the Port Kembla Breakwater (starting near the Port Kembla Boat Ramp at the north end of MM Beach). About a kilometre along the rock wall, looking down toward the sheltered harbor side, a resident fur seal can be spotted lounging on a flat rock roughly 75% of the time.
High-Tech Mapping: Drones, Thermal Sensors, and Radiator Fins
To monitor how the seal population fluctuates throughout the year, Professor Hamylton and a UOW honours student named Lewis conducted monthly aerial surveys over Martin Island. Operating from a university research boat, the team launched automated drones programmed to fly grid lines over the island at an altitude of 60 metres.
Back in the lab, over 800 high-resolution images were stitched together into a seamless photogrammetry mosaic with a crisp two-centimetre spatial resolution. Counting the colony proved to be an extreme game of biological "Where's Wally?" because grey-brown fur seals blend seamlessly into grey-brown rocks. In fact, many of the natural rock formations on Martin Island are literally seal-shaped! To solve this, the team experimented with early-morning thermal drone flights to spot the animals' body heat before the sun warmed the surrounding stone.
The survey revealed that the colony fluctuates seasonally, peaking at approximately 140 seals around September and October. Seals are thermosensitive; their thick layer of blubber makes it difficult to cool down in warm water. On warmer days, you will often spot seals "sailing" on their sides in the ocean with a single flipper raised in the air. Far from waving at passing boats, the seal is using its un-furred flipper as a biological car radiator, circulating blood through the air and water to dump excess body heat.
Beneath the surface, the marine environment surrounding the Five Islands shifts between bare "urchin barrens" (rock covered in pink calcified coralline algae) and dense kelp forests. As a keystone species, golden kelp creates a complex structural habitat that shelters fish, squid, and octopus, providing a rich hunting ground for the seals.
Ancient Volcanoes, Dharawal Law, and Marie Tharp
During the episode, Professor Hamylton read an excerpt from her book, Plotting the Oceans, which beautifully connects scientific cartography with cultural landscape stories.
Long before European explorers charted the coast, the Dharawal people—specifically the local Wadi Wadi clan—preserved the creation story of the Five Islands. As knowledge holder Auntie Carol Speechley explains, the islands formed when Oola-boola-woo (the powerful west wind living atop the escarpment) grew angry with his five disobedient daughters: Mimosa, Wilga, Lillipilly, Wattle, and Clematis. He blew the five sisters out to sea along with the mountain rocks they sat on, leaving them stranded in the ocean. The sixth sister remained loyal on the mainland, transforming into Mount Keira. Far from a simple fairy tale, this Dreaming narrative encodes traditional Aboriginal law regarding respect for country and community conduct.
Remarkably, modern geological mapping reveals a striking parallel to this story. The Five Islands were formed by intense volcanic activity approximately 250 million years ago. Geological analysis shows that the island rocks share the exact same chemical strata and mineral signatures—known as Dapto, Saddleback, and Bombo latite—as mainland volcanic peaks.
In Plotting the Oceans, Sarah also spotlights pioneering cartographer Marie Tharp. Working out of Columbia University in the 1950s, Tharp was banned from research ships because of her gender. Instead, she painstakingly plotted thousands of ocean depth soundings by hand on massive tables.
Tharp discovered the Mid-Atlantic Ridge and the central Rift Valley, providing the foundational visual evidence for continental drift and plate tectonics. Her work was initially dismissed as "girl talk" until French oceanographer Jacques Cousteau towed a camera sled behind the Calypso in 1957, filming the rift valley floor exactly where Tharp had mapped it.
Recommended Local Spot: To connect with the 250-million-year-old volcanic geology featured in Sarah's book, take a trip down to Bombo Headland Quarry in Kiama. Walking among the geometric basalt columns allows you to touch the exact latite rock signature that ties our mainland to the Five Islands offshore. Afterward, drive up to Saddleback Mountain Lookout to stand on the rim of the ancient, extinct volcanic crater that hurl-shaped this coastline.
Equity in the Field: Co-Founding WICGE
In addition to her research and writing, Professor Hamylton is a passionate advocate for diversity in science. Ten years ago, she co-founded the Women in Coastal Geoscience and Engineering Network (WICGE, or "Wiki").
An early survey conducted by the network gathered responses from over 300 women in coastal science, unearthing systemic barriers, field isolation, and safety challenges. In response, WICGE developed formal field codes of conduct and safety protocols that universities and research institutions now implement globally. These frameworks ensure that remote field trips, research vessels, and island surveys are safe, equitable, and inclusive environments for the next generation of female scientists.
Catch the Conversation
To hear Professor Sarah Hamylton read directly from Plotting the Oceans, describe being dive-bombed by protective seagulls, or detail her early career diving on coral reefs in Fiji, stream the full episode, "Marine Cartography & Coastal Science // Professor Sarah Hamylton," on Spotify, Apple Podcasts, or your preferred audio platform.