Dive slate · divesites.com.au · printed 9 Nov 2026
Line of Sight (Holmes Reef)
Coral Sea, External Territories · near Cairns (liveaboard)
| Depth | Max 30 m |
|---|---|
| Minimum level | Advanced Open Water |
| Difficulty | Advanced |
| Access | Boat (multi-day/liveaboard) |
| Entry | Giant stride from liveaboard dive deck; descend mooring or line |
| Current | Strong |
| Visibility | 20-40 m |
| Water | summer 28-29 °C, winter 24-26 °C |
| Suit | 3 mm full wetsuit or lycra Nov–Apr (27–29°C); 5 mm full wetsuit Jun–Sep (23–25°C); full-length lycra or stinger suit recommended Nov–May |
| Best season | Year-round when weather allows; Sep–Dec usually calmest and clearest (visibility can exceed 40 m); Jun–Aug stronger SE trades make the open-ocean crossing rough; Dec–Apr cyclone season |
| Bottom time | 40 min |
| Position | not published |
| Permit | Coral Sea Marine Park (Parks Australia). Scuba/snorkel tourism in all zones requires Parks Australia authorisation (held by the operator); recreational fishing is prohibited in National Park Zones. Holmes Reefs are zoned Habitat Protection Zone (Reefs) (IUCN IV) under the Coral Sea Marine Park Management Plan 2018 – recreational fishing is allowed, so expect occasional fishing vessels. |
| Nearest chamber | Townsville University Hospital hyperbaric unit (Townsville) – aeromedical evacuation only after the vessel steams back toward the coast; several hours to more than a day away; liveaboards carry oxygen and satellite communications |
| Emergency | 000 · DAN Asia-Pacific diving emergency 1800 088 200 |
Line of Sight (Holmes Reef)
A drift along the ridge in the channel between the two Holmes atolls.
Near Cairns (liveaboard) · Coral Sea, External Territories
- Depth
- Max 30 m
- Minimum level
- Advanced Open Water
- Access
- Boat (multi-day/liveaboard)
- Boat ride
- —
- Water
- 28-29 °C
- Visibility
- 20-40 m
Line of Sight (Holmes Reef)Max 30 m · Advanced Open Water
Dive factsDepths, conditions, location & safety
Season
In season nowBest months: January, February, March, April, June, July, August, September, October, November, December.
Year-round when weather allows; Sep–Dec usually calmest and clearest (visibility can exceed 40 m); Jun–Aug stronger SE trades make the open-ocean crossing rough; Dec–Apr cyclone season
- Best months
- Now (November)
- Stinger suit Nov–May
Dive facts
- Depth
- Max 30 m
- Typical depth
- 18 m
- Certification
- Advanced Open Water
- Difficulty
- Advanced
- Depth tier
- Advanced Open Water (18–30 m)
- Access
- Boat (multi-day/liveaboard)
- Offshore
- 240 km
- Dive centre needed
- Yes – boat access only
- Shore / independent
- No
- Current
- Strong
- Visibility
- 20-40 m
- Water temp (summer)
- 28-29 °C
- Water temp (winter)
- 24-26 °C
- Water
- Tropical
- Bottom time
- 40 min
- Dive traffic
- Moderate (occasional charters/club dives)
- Night dive
- No
- Snorkel friendly
- No
Exposure suit
3 mm full wetsuit or lycra Nov–Apr (27–29°C); 5 mm full wetsuit Jun–Sep (23–25°C); full-length lycra or stinger suit recommended Nov–May
Location
Holmes Reef – between East and West Holmes · Coral Sea – Holmes Reef
No published coordinates. The map above shows the general area, estimated from other documented sites near Cairns.
Dive site map (external) →Primary source: marinelife.org.auMarine park & permits
Coral Sea Marine Park (Parks Australia). Scuba/snorkel tourism in all zones requires Parks Australia authorisation (held by the operator); recreational fishing is prohibited in National Park Zones. Holmes Reefs are zoned Habitat Protection Zone (Reefs) (IUCN IV) under the Coral Sea Marine Park Management Plan 2018 – recreational fishing is allowed, so expect occasional fishing vessels.
Nearest recompression chamber
Townsville University Hospital hyperbaric unit (Townsville) – aeromedical evacuation only after the vessel steams back toward the coast; several hours to more than a day away; liveaboards carry oxygen and satellite communications
Diving emergency: call 000, then DAN AP 1800 088 200.
Trip planner
Build a trip around Line of Sight (Holmes Reef) →
A day-by-day plan for Coral Sea with this site locked in.
This guide is a planning aid. Conditions change daily — confirm with a local dive centre and dive within your training. Data & safety notes.
Dive profile
How this site rates
Scores are computed from the recorded data, not opinions. How?
At a glance
Line of Sight (Holmes Reef) is a drift liveaboard-only site in Coral Sea, Australia's external territories, to a maximum of 30 m, suited to Advanced Open Water divers, strong current.
Rated advanced because of depth beyond 18 m, strong current.
Why dive here
- A drift along the ridge in the channel between the two Holmes atolls.
- Visibility often reaches 20-40 m.
About Line of Sight (Holmes Reef)
Line of Sight is a drift dive at Holmes Reef along a ridge between the two reefs that make up the Holmes system.
Holmes Reef consists of two atolls, East and West Holmes, separated by a channel. A submerged ridge in the channel concentrates tidal flow between the two lagoons and the open ocean, which is why the site is dived as a drift. The name probably refers to the straight line of the ridge, which divers follow from one end to the other.
No detailed species list is published. Channel ridges in the Coral Sea typically attract schooling fish such as trevally, fusiliers and barracuda, and predators such as grey reef sharks, dogtooth tuna and mackerel, and support hard corals and fans adapted to current. Those are general expectations rather than documented observations.
Line of Sight suits experienced divers comfortable in current, with good buoyancy control and experience ascending under an SMB in open water. The crew will choose the tide and direction; if the current is too strong, another site will be substituted. Depths and location in this record are estimates.
For divers on a Holmes itinerary it offers something different from the pinnacle at Nonki and the caves at Amazing: a fast, open ride through the channel between the two atolls, where the ridge funnels the flow.
Getting there & entry
A drift dive along a ridge between the two Holmes reefs, sometimes in strong current.
Liveaboard only. Mike Ball's Spoilsport includes Holmes Reef on its 7-night Coral Sea exploratory (Cairns return), the 7-night Yongala & Coral Sea expedition (Townsville to Cairns) and the 10-night Coral Sea Odyssey; the overnight crossing from Cairns is about 240 km of open ocean. Holmes is normally allocated a day on these itineraries.
Line of Sight is run as a drift from a tender along the ridge between the two Holmes atolls.
Entry: Giant stride from liveaboard dive deck; descend mooring or line
Weather, swell & tides
Holmes Reef is a pair of isolated Coral Sea atolls about 240–250 km east of Cairns with no land for shelter. Dive the World calls it a fair-weather destination: SE trades over about 20 knots (common June–August) make the crossing and surface conditions rough, although the lagoons and western sides offer some protection. Currents are normally gentle but can be strong in the channels and on the ridges, especially on a falling tide.
September–December usually has the calmest seas and 20–40 m visibility; December–April is cyclone season.
Best season: Year-round when weather allows; Sep–Dec usually calmest and clearest (visibility can exceed 40 m); Jun–Aug stronger SE trades make the open-ocean crossing rough; Dec–Apr cyclone season
How the dive is usually run
Drop from the tender at the up-current end of the ridge, descend to the ridge crest and drift along it at the briefed depth, watching the blue on either side. Ascend under an SMB at the planned time for pick-up.
Marine life
- Expected channel fauna: trevally
- fusiliers
- barracuda
- grey reef sharks →
- dogtooth tuna
- mackerel; hard corals and fans
Linked species have their own page listing every site where they are recorded. All marine life →
Training required
Beyond 18 m an Advanced certification (which includes a deep dive to 30 m) is the accepted minimum. Anything past 25 m is a deep dive in practice.
At more than 25 m this counts as a deep dive: watch no-decompression limits and gas.
Courses that help here
- Enriched Air Nitrox – Longer no-decompression time at 25 m and deeper.
- Drift Diver – Current is a feature of the dive.
Depth tiers: 0–10 m easy · to 18 m Open Water · 18–30 m Advanced (25 m+ is a deep dive) · 30–40 m Deep specialty · 40 m+ technical. All courses
Hazards & warnings
Strong current at times; SMB and tender pick-up essential; remote – hours to days from medical help.
Dive centres that go here
Coral Sea liveaboards visiting Holmes Reef – occasional.
Operators recorded for Line of Sight (Holmes Reef)
Other dive centres in Coral Sea
Spirit of Freedom
ListedCairns · Cairns · QLD
An expedition liveaboard associated with Ribbon Reefs, Osprey Reef and Coral Sea itineraries.
spiritoffreedom.com.au · (07) 4047 9150
Passions of Paradise
ListedCairns · Cairns · QLD
A Cairns sailing catamaran day trip combining reef diving and snorkelling.
passions.com.au · (07) 4041 1600
Divers Den
ListedCairns · Cairns · QLD
A Cairns operation running both day-boat and liveaboard products alongside a training business and retail presence.
diversden.com.au · (07) 4046 7333
Down Under Cruise & Dive
ListedCairns · Cairns · QLD
A Cairns day-boat operator offering reef diving, snorkelling and introductory diving.
downundercruiseanddive.com.au · (07) 4052 8300
Reef Encounter
ListedCairns · Cairns · QLD
A Cairns-based liveaboard vessel offering multi-day reef stays with day-boat transfers.
reefencounter.com.au · (07) 4037 2700
Pro Dive Cairns
ListedCairns · Cairns · QLD
A long-established Cairns operation best known for multi-day liveaboard certification trips that combine Open Water training with outer Great Barrier Reef diving.
prodivecairns.com · (07) 4031 5255
General area
No position has been published for Line of Sight (Holmes Reef). The circle shows where it is likely to be, worked out from other documented sites near Cairns. Ask a local operator for the exact site.
Dashed circle: general area (about 60 km), from other documented sites near Cairns. 6 pinned sites. Pins marked approximate on their pages show the general area only; not for navigation.
Line of Sight (Holmes Reef): frequently asked questions
How deep is Line of Sight (Holmes Reef)?
Line of Sight (Holmes Reef) reaches a maximum depth of 30 m; most of the dive is spent around 18 m.
What certification do I need to dive Line of Sight (Holmes Reef)?
Advanced Open Water is the recommended minimum. At more than 25 m this counts as a deep dive: watch no-decompression limits and gas. Rated advanced because of depth beyond 18 m, strong current.
Can I shore dive Line of Sight (Holmes Reef)?
No, it is reached by boat. A dive centre is required: boat access only.
When is the best time to dive Line of Sight (Holmes Reef)?
Year-round when weather allows; Sep–Dec usually calmest and clearest (visibility can exceed 40 m); Jun–Aug stronger SE trades make the open-ocean crossing rough; Dec–Apr cyclone season.
What marine life will I see at Line of Sight (Holmes Reef)?
Regularly recorded: Expected channel fauna: trevally, fusiliers, barracuda, grey reef sharks, dogtooth tuna, mackerel; hard corals and fans.
What wetsuit do I need at Line of Sight (Holmes Reef)?
3 mm full wetsuit or lycra Nov–Apr (27–29°C); 5 mm full wetsuit Jun–Sep (23–25°C); full-length lycra or stinger suit recommended Nov–May.
How cold is the water at Line of Sight (Holmes Reef)?
Typically 28-29 °C in summer and 24-26 °C in winter.
What are the main hazards at Line of Sight (Holmes Reef)?
Strong current at times; SMB and tender pick-up essential; remote – hours to days from medical help. See the hazards section above for the full list.
Where is the nearest recompression chamber to Line of Sight (Holmes Reef)?
Townsville University Hospital hyperbaric unit (Townsville) – aeromedical evacuation only after the vessel steams back toward the coast; several hours to more than a day away; liveaboards carry oxygen and satellite communications. In an emergency call 000, then DAN Asia-Pacific on 1800 088 200.
Diving in Coral Sea
Beyond the outer Great Barrier Reef the continental shelf drops away and a scatter of isolated oceanic reefs rises from 1,000 m or more of water. Osprey, Bougainville, Holmes, Flinders and Lihou reefs have vertical walls, 40 m-plus visibility, and shark populations that were never fished down. North Horn at Osprey is the best-known shark dive in Australia; the southern reefs are visited by a handful of boats a year.
Getting there: Liveaboard only, 4–7 nights from Cairns or Port Douglas for Osprey and the northern reefs; expedition trips from Cairns or Townsville for Flinders and Lihou. Overnight crossings of open sea are part of the deal.
Sources
Data confidence: Low · Being verified: Depths, location and marine life not documented.. Last updated September 2026. Know this site better? How to send a correction
