Quarantine Bay, 3 km south of Eden, is the town's main boat ramp and a pleasant reserve with toilets, picnic tables and fish-cleaning tables. It was the site of a quarantine station in the 1800s. Eden's tourism site describes resident seals and stingrays, which gather around the cleaning tables when fishers return.

The bay has a sandy bottom with rocky edges and some seagrass and kelp. Big smooth stingrays and eagle rays are regular visitors, particularly near the ramp, and fur seals often cruise the bay. Fish include bream, luderick, leatherjackets, flathead and whiting, with blue groper and wrasse on the rocks. Octopus, cuttlefish and nudibranchs are found around the rocks and weed.

The site suits snorkellers and new divers wanting a sheltered, shallow swim with a good chance of rays and seals. The main hazard is boat traffic from the four-lane ramp, especially on calm mornings when everyone is heading out, so stay well away from the ramp and use a dive flag. Divers leaving on boat trips from here often have time for a snorkel while waiting. Don't feed the seals or stingrays, however tame they appear. The reserve is also a good place to watch whales in spring, and pelicans are usually around the cleaning tables. Divers waiting for a boat trip often snorkel here first, and it makes an easy check-out dive for new gear or weighting before heading out to deeper Twofold Bay sites.

From Eden drive about 3 km south on the Princes Highway and turn left to Quarantine Bay, following signs to the boat ramp and reserve. There is plenty of parking, toilets, picnic tables, fish-cleaning tables and boat-washing facilities. Enter from the beach well to one side of the ramp.

This is also the main launch point for boat dives to the Eden tugs and Green Cape.

Twofold Bay faces east. Its northern and southern shores give shelter from southerly and northerly swell respectively, but strong easterly swell rolls straight into the bay. Visibility is often good by NSW standards but drops after heavy rain, when the Towamba River and Nullica River flush into the bay, and during strong winds.

Quarantine Bay is on the western side of Twofold Bay and fairly sheltered, but it is busy with boats on calm mornings. Dive at quieter times, away from the ramp.

Enter from the beach away from the ramp and snorkel or dive along the rocky edge of the bay at 2–6 m, watching for stingrays on the sand and seals around the fish-cleaning tables. Stay out of the boat lane.

No operator lists it as a dive site; Eden's tourism pages note resident seals and stingrays. It is the departure ramp for many Eden boat dives.