Meet the site
Seal Island is a small limestone island in Shoalwater Bay, a short hop north of Penguin Island, where Australian sea lions haul out to rest. It is one of three places near Perth where the public can reliably see sea lions, and snorkel cruises from Rockingham come here to let visitors watch them in the water. The island itself is closed to landing.
Underwater, the island is ringed by shallow limestone reef, sand and seagrass in 1–6 m. The reef has small ledges and overhangs with buffalo bream, wrasse, sweep, herring cale, leatherjackets and seasonal baitfish schools, and the seagrass holds cuttlefish, rays and pipefish. The main attraction is the sea lions: mostly young and adult males that travel from breeding colonies further north. They are curious and playful in the water and may swim close to snorkellers. Bottlenose dolphins and little penguins from Penguin Island also use the bay.
Australian sea lions are an endangered species and unpredictable. Keep at least 10 m away, let them decide how close to come, never approach animals on the beach, and do not feed or touch them. Sea lions have bitten people. Operators follow DBCA wildlife interaction guidelines, and private boats should do the same.
The site suits snorkellers and divers of all levels who want a sheltered, shallow wildlife encounter. Visibility is usually moderate. Combining Seal Island with Penguin Island and the Point Peron reefs makes an easy half-day in Shoalwater Islands Marine Park, with short boat runs between each stop.
Research this site before booking Stored site notes may be historical. These questions highlight gaps without turning old instructions into a current dive plan.
Seal Island (Shoalwater) is recorded as Island in Perth. The listed access is boat. Confirm the actual meeting point, route and permission to visit; a map pin does not establish any of these.
Topics flagged by the stored research
These are questions prompted by the existing notes, not a verified or complete hazard assessment.
- Other water users
- Ask about vessel activity, exclusion areas and the agreed surface arrangements.
- Water movement
- Ask how swell and local exposure affect the proposed entry, exit and route.
Historical access notes exist for this record, but have not been independently verified for current use. Request current directions from the operator or site manager rather than following an old entry description.
Questions, answered
Is Seal Island (Shoalwater) suitable for my certification?
The record lists Snorkel/Any. That does not establish suitability for every route or day. Share your training, recent experience and equipment needs with the operator and ask about the specific proposed dive.
Can I book Seal Island (Shoalwater) through YouDive?
YouDive is an independent research directory. Contact an operator directly to confirm whether it currently runs the trip, the inclusions and the booking terms.
What you might see
Australian sea lions (mainly males), bottlenose dolphins, little penguins, buffalo bream, wrasse, sweep, herring cale, leatherjackets, baitfish schools, cuttlefish, rays, pipefish
Location
Small limestone island north of Penguin Island in Shoalwater Bay, a haul-out for Australian sea lions; landing is prohibited.
Facilities nearby
Launch facilities at Mersey Point and Point Peron (parking, toilets); cruise departures from Rockingham.
Before you make plans
Conditions, access and operator schedules can change. This is a location guide, not a dive plan. Ask a local operator about current conditions and suitability for your training and experience.
Sources & further reading
exploreparks.dbca.wa.gov.auperthisok.comdivessi.comtrailswa.com.auRecord updated 27 Sept 2026. Source claims are being reviewed.
