Bylund's Pass, also known as Viv's, lies just outside the Heron Island harbour entrance, making it one of the closest dives to the jetty. The reef slope here is coated with an amazing amount of hard coral, and the constant water movement in and out of the harbour area keeps it healthy and busy. The coral slope is alive with small fish moving through the branches and plates, and the site's regular turtles can be seen feeding in the current, often allowing divers to approach closely.

The dive team advises keeping one eye on the open water, because large numbers of great barracuda usually lurk out there, hanging almost motionless in the current. Other pelagic visitors are common for the same reason. Current is a feature of the site, and dives are typically planned with it, either near slack water for a relaxed exploration of the slope or as a gentle drift.

Divers should stay on the reef and away from the harbour channel, where the resort's boats and the ferry pass. Bylund's Pass suits Open Water divers comfortable with some current. Its proximity to the jetty makes it a convenient choice when conditions elsewhere are poor or as a quick afternoon dive.

Published depth information is limited, so the figures given here are estimates based on the reef slope around the harbour entrance. The site is good for photographers who like hard-coral landscapes and schooling barracuda in the background. It is also a useful site for a final dive before the no-fly interval, as the short boat ride leaves more time for rinsing and packing gear.

Heron Island is 72 km north-east of Gladstone. Fly or drive to Gladstone, then take the Heron Islander ferry from the Gladstone Marina terminal (72 Bryan Jordan Drive; check-in from 7:45 am, departs 9:30 am on scheduled days, about 2 hours), or transfer by seaplane or helicopter. Dive gear is carried on the ferry in addition to baggage.

On the island, the dive centre sits beside the harbour; boats leave the jetty for three dives daily and most Heron Reef sites are 5-15 minutes away. Bylund's Pass (also called Viv's) is just outside the harbour entrance, only 2-5 minutes from the jetty.

Heron Reef sites are chosen on the day by wind and tide. The prevailing south-east trade winds (strongest April-September, often 15-25 knots) make the southern and south-eastern reef edge rough, so the sheltered northern and western sites are dived most. Northerly winds in spring and summer reverse this.

The tidal range is up to 3-4 m and currents run strongly around the reef edge and through Wistari Channel on springs; visibility is usually best on the incoming tide. Cyclone season is November-April; summer storms and plankton blooms can drop visibility to 10 m. Stingers are uncommon this far south but present in summer.

Being close to the harbour channel, the site has a noticeable tidal current that the turtles use for feeding; dive it near slack or as a gentle drift, and stay clear of the channel itself because of boat traffic.

Descend onto the reef slope and follow it with the current, staying at 10-15 m among the hard corals and keeping an eye on the blue for barracuda. Turn or drift to the pick-up point, ascending up the slope for the safety stop away from the harbour channel.

Heron Island Resort Dive Centre is the only operator: three guided boat dives a day (about 9 am, 11 am and 3 pm) plus scheduled night dives, from the resort jetty; sites are rotated by tide and wind. Access requires a stay at Heron Island Resort (or the University of Queensland research station).