Approximately 28000 vehicles per day cross the twin bridges of the Pacific Highway spanning the Swansea Channel, very few of these people realise they are travelling over one of New South Wales best dive sites which features an amazing abundance of sea life. With easy access, a maximum depth of 14 metres and not being affected by sea conditions, the site is suitable for all levels of divers.
History of Swansea Bridge
The first bridge crossing the Swansea Channel was constructed in 1881 by A & R Amos as a railway bridge to transport stone for the construction of the Southern channel wall and breakwater. This bridge was constructed of timber which was harvested from the Western side of Lake Macquarie and processed at a sawmill at Adamstown, the timber was then transported to the building site by bullock teams. The opening span was originally used on a bridge at Black Wattle Bay in Sydney Harbour and was relocated to Swansea when that bridge was updated.
Following the completion of the channel wall in 1885 ownership of the bridge was taken over by the Public Works Department, the railway tracks were removed and the bridge was opened to the public. The first bridge appears to have been located to the east of the current eastern bridge.
By 1908 the first bridge was suffering badly from wood rot so the Public Works Department contracted Peter Callan and Sons of Newcastle to construct a new timber beam bridge with a steel girder bascule opening span. The new bridge was completed at a cost of £6,180 and featured a single traffic lane. Components which originated from the Black Wattle Bay bridge were reused again in the new bridge.
The bridge served without any major problems until the 1930s when traffic volumes became too high for the single lane bridge. A series of motor vehicle collisions and incidents involving pedestrians resulted in calls for the bridge to be widened however this was not a practical solution. As a temporary measure flag men were stationed at each end of the bridge to control the ever increasing traffic volumes. This bridge was located where the eastern most bridge stands today.
In the early 1950s work started on a new bridge located to the west of the second bridge. The bridge featured a two-bascule opening span with underneath counter weights, this eliminated the need for an overhead bridge structure. The opening spans were constructed of an open grid pattern material which reduced the weight allowing the use of a smaller counter weight. The main deck of the bridge was constructed of steel girders and concrete. The main components of the opening span were manufactured by M.A.N in Germany and shipped to Australia. The new bridge was opened on the 14th of December 1954 and is still in operation today. This bridge carried traffic in both directions until another bridge was constructed next to it in 1989, now it carrys northbound traffic only while the bridge constructed in 1989 carries South bound traffic.
Diving Swansea Bridge.
Due to the strong tidal currents in the channel, the bridge can only be dived at high or low tide. Few people bother diving on the low tide due to the extremely poor visibility caused by the water exiting Lake Macquarie. High tide in the channel occurs approximately 2.5 to 3 hours after the advertised ocean tide times. The time difference varies with the size of the tide and variations of atmospheric pressure. Your best bet when planning a dive at Swansea bridge is to contact the Snorkel Safari dive shop on 02 49720 940 and ask them for the current tide times.
You can find the Swansea ocean tide times here.
The site has three main entry points. The most popular being the boat ramp on the South Western side of the bridge. When entering from this location you can either park in the car park behind the boatshed or in the Woolworth’s car park and walk down the laneway next to the Aqua Zero dive shop. This is the easiest entry point. If you intend to park in the boatshed car park you will need to arrive early.
The second entry point is via the stormwater drain located in front of the RSL club. This is a good alternative to the boat ramp when parking is not available there. Parking is available in Chalmers Street and in the RSL car park. To utilise this entry point you will need to climb down some rocks, it is not a difficult climb.
The third entry point is via the dirt car park located on the North eastern side. Entry here is gained by climbing down the rock wall near the foot of the bridge. This climb is more difficult than the one in front of the RSL club. The RTA often uses the car park as a depot when conducting work on the bridge so this area is often closed to the public.
When starting the dive at the boat ramp you will immediately drop down to a depth of 6 metres. As soon as you reach the bottom you will notice a small reef made up of scuttled shopping trolleys and pushbikes, just off the channel wall. There are some great things to see here including sea horses but don’t waste your tide time at this stage as you can spend plenty of time here at the end of the dive as the tide starts running out. Most divers follow the channel wall east to the bridges and spend most of their bottom time exploring around the piers.
Points of Interest
Mainspan Utility Pipes
The western bridge carries three large utility pipes across the channel which are secured to the western edge of the bridge. At the opening span these pipes drop down to the utility pipes decend down to the bottom of the channel then make a 90 degree turn and run parallel to the channel floor. The sand in this area shifts around a lot. At times there can be a 2 -3 metre gap between the pipes and the channel floor and other times the pipes can be buried. When the pipes have been exposed for a reasonable period of time they become the foundation for some pretty marine growth. If you put your macro eyes on you will see some great little creatures including small crabs and pipe blennies. Large schools of snapper, bream, king fish and red morwong seem to congregate in this area too. If the visibility is really clear there is a great photo opportunity looking up at the timber fenders from below.
Northern Bascule Foundation (Western Bridge)
After you cross the main span you will see the utility pipes turn upwards and head for the surface. You will see a large square heavy duty pylon which forms the base for the northern opening span. If you drop down to the channel floor you will find an overhanging ledge under the North West side of the structure. Have a look under this ledge and there is a good chance you will see many pineapple fish and occasionally a crayfish or two. There is a large mangrove jack who inhabits this spot from time to time. This shelf was one of the locations that was saved from being buried during the 2006 works in the negotiations between the RTA and dive industry.
North of Mainspan to Northern Wall
Moving north of the main span there are fewer significant features but the sea life is still very abundant. It is interesting to look to the shifting sand dunes to the north west some of these dunes can be up to 5 – 6 metres high, depths of 14 metres can be reached in this area at times. The area towards the Northern wall tends to be subject to less current than other areas and visibilty tends to be better here too. Large schools of trevally and luderick regularly congregate in this area and sunlight seems to filter down from the bridge providing a serene atmosphere. In the summer months schools of surgeon fish also congregate here. There are a number of old pylons remaining from the second bridge which stood where the eastern bridge stands now, these pylons have been cut off and now stand about 1 metre above the channel floor.
Play things left by RTA in 2006
Following the works in 2006 the RTA scattered various items under the bridge to replace the reef structure they buried, these items included concrete pipes, reef balls, disused machinery and other assorted rubble. These items are scattered throughout the site and have become home to many marine creatures. Some of these items have become play things for some of the more adventurous divers.
Bridgework and Major Changes to the Site
Work to secure the bridge foundations conducted in 2004 and 2006 has considerably altered the topography of the channel floor. Prior to 2006 the bottom consisted of shifting sands and remnants of the old bridges which provided shelter for sea life. In 2004 Gravel was packed around the base of several peers of the Western bridge North of the opening span. This work had little impact on the site compared to the work that was done in 2006. In mid 2006 the RTA announced it was going to dump a layer of railway ballast on the channel floor 1 to 3 meters thick for the entire length of the bridge.
The RTA consulted with the local dive industry and some concessions were made. The RTA agreed to use a more coarse type of gravel and keep certain areas clear of gravel. A plan was made for the local dive shops to collect rocks, debris and immobile sea life from the channel floor and place them in baskets provided by the RTA. These baskets were to be moved to another location while the work was carried out then moved back when the work was finished.
The baskets were provided and the dive shops loaded them as planned. Some of these baskets were moved to an area in front of the RSL club but the vast majority were never moved as promised and were buried with rocks. Several of these baskets are still visible.
As a result of this work the dive site is not as deep as it used to be and the visibility is generally not as clear either.