Rivers and river crossing
bridges and flying foxes
It pays not to look down, but instead stare ahead on wire bridges. Place your feet at an angle to the wire, with the wire under the foot arch.
Be very careful to stay clear of any cranks in the cage of a flying fox if someone else is winding you across. Leave the cage untied for others to access it from either side. Under no circumstances try to grab, or hold onto the cables.
Some skill, practice and courage is required to jump from boulder to boulder to cross with dry feet. Not all of your party will necessarily have sufficient confidence. Ensure that there is no snow, or mud clinging to your boot soles and in winter beware of sometimes invisible films of ice on the rocks, especially on frosty mornings.
The most important part of fording a river is to assess it and confirm that fording will be safe. Identify the best place to cross (it may be upstream, or downstream of the recommended ford), perhaps by climbing a tree for a better view. Check ‘crisis points’ in the river where things could go wrong, escape routes, the force of the river and assess the river bed (is it shingle or boulders?). As you cross, keep asking yourself if you are safe.
Rivers usually fall as fast as they rise after rain. Glacial rivers are often lower early in the morning before the daily melt starts.
Rivers range from wide, braided, shingle Canterbury rivers to steep, bouldery Westland cataracts and everything in between; each requires its own treatment. In general, look for good fords:
- Where the river is wide (it may be faster flowing, but fast, shallow flow is often easier to cross than a slightly slower, deep flow)
- Where the water is shallowest, often just at the top of rapids,
- Upstream of where two channels join,
- Where the river runs in several channels as these are easier to cross than one big one (although, make sure that you are always aware of your retreat route in case you need it),
- Between bends, where the water is quieter,
- On long, diagonal shallow gravel bars that can traverse the whole river width, but watch for the potential final, deep section.
Take care with:
- Glacial rivers, as their opaque water may hide boulders,
- Bends in the river, as the water scours deeper channels near the outside bank. Even on slight curves and streams these need care,
- Junctions of channels where deep scour of the river bed is very common downstream, the flow is strong and the bottom mobile.
Do not wade a river if:
- The river if flowing faster than a moderately fast walking pace, or the velocity in metres per second times the depth in metres is greater than 1 m2/s,
- Boulders are knocking from the river flow,
- The river is running a fresh, or in flood,
- Trees, branches, or logs are flowing down the river,
- You find gravel is being sucked out from under your boots (i.e. mobile river bed),
- The crossing point takes you to the outer side of a curve in the river, especially if it is a sharp bend as there is likely to be a deep channel there,
- A normally clear river is heavily discoloured, unless you are very sure of the ford.
Cross diagonally downstream so that you do not have to fight the current when placing your feet: the faster the river, the more ‘drift’ down river you will have to allow to reach the far side.
If possible, just shuffle along with small steps. This helps you to keep control of your legs and your balance.
Be aware that once the river level rises to catch your pack, the force from the current will increase dramatically and at the same time your feet will have less grip as you start to float.
Minimise the force of the water by removing over-trousers. Keep the waist-belt buckle done up.
While the printed edition of this manual advises to keep the sternum strap done up also, it is now considered best practice is to undo it before entering the water. In the event of a swim, the pack’s buoyancy causes it to shift upwards compared to the tramper’s body, with the sternum strap coming to rest against the tramper’s throat or under their chin. Combined with the force of the water, this could cause strangulation.
Always keep your boots on. If you are expecting prolonged snow travel afterwards, remove you dry socks before entering the water. Once crossed, replace your socks, put your feet inside plastic bags, and then back into the boots.
Don’t stare at the water, or lean down to grab onto something below the water surface as it will disorientate you.
If you come unstuck, lie back on your pack which will provide considerable buoyancy and haul down on your pack-straps to avoid the pack bobbing up over your head. In rapids and shallow water, the risk of head injury is high. Always keep your feet at the surface and pointing down river, and maneuver to the next safe exit point by paddling with your hands. Having your feet at the surface greatly reduces the risk of your feet becoming trapped under a boulder. With a trapped foot, the current can force the rest of your body under water, resulting in drowning. Having your feet pointed down river allows you to use your legs as ‘shock absorbers’ should you be forced against rocks or obstacles, and obviously protects the more important bits of your body (torso/head).
Jumping into a glacial river risks a momentary shock to the body; this can essentially immobilise the body’s muscles for a few minutes, which can lead to drowning.
Any deep crossing, or continued river crossings will chill your body so in cool weather be alert to your muscles losing strength due to the cold and the onset of hypothermia.
Crossing with mutual support
The strongest and most experienced person takes the upstream position to break the force of the current and lead the crossing; weaker members are in the wake of the leader and so out of the main current and their job it to support the leader. It is vitally important to keep the party parallel to the current and in the wake of the leader at all times. A reasonably capable person should be on the downstream end and if the force of the river is at all strong, the second person in line needs to be strong enough to support the leader – it is imperative that the leader does not fail.
Be aware that the force of the river on you may be indistinguishable from forces from other members of the party, which in turn may be from the river acting on them and so not necessarily desirable. Make sure everyone communicates clearly.
Move into the river under command of the upstream person who will also direct the speed of travel and make sure that the party is staying in his wake. If the crossing is too difficult, retreat by backing out. Try and avoid getting to this position.
The greatest risk to the party is when someone gets washed off their feet, in which case entangling limbs can jeopardise the whole party. Keep calm and make sure everyone works as a team to get out back in control.
There is no single, best way to cross with mutual support: varying heights of party members, composition of the river bed, state of the flow and personal preferences will influence your choice.
Standard pack-strap method
This technique makes for a very secure unit and because the members are essentially locked together, prevents anyone washing away should they let go. It is the most commonly taught technique. However, it can be awkward where the river bed is bouldery and uneven.
Reach behind adjacent people’s backs, or over them if they are short (as for the over shoulders pack-strap method below), and grasp the further pack-strap.
Over shoulders pack-strap method
This technique is not as secure as the above method, but allows for some flexibility when crossing uneven, bouldery river beds. It works best for three to five people of about the same height. Each person reaches across the next persons’ pack and holds onto the further shoulder straps.
This is a method that some early explorers described Maori to have used and provides the securest support to the up-river person in strong currents. Use a strong pole capable of supporting a person’s weight, five to six centimetres thick and two to three metres long (for four to six people). Interlink your arms with your neighbours’ before grasping the pole. It is usually best for the upstream person to hold the thinner end to ensure they have a very secure grip. Under no account should anyone let go their grip on the pole as they may be lost: this is a serious shortcoming of this method. The pole method allows considerable flexibility to deal with uneven river beds, while maintaining integrity. More than 12 people at once can cross on a sufficiently long pole, or log.
Solo pole method
Use a strong pole up to about two metres long, or a long ice-axe as a support. Hold the pole upstream and use it as a third leg to ensure that there are always at least two points of contact when moving.
Rope methods can enable parties to safely cross rivers that would be impossible for any of the above methods. They are not described here. A thorough understanding of the techniques is required. Using a rope as a handrail without a belay and proper setup is extremely dangerous. More information on rope crossings is available in this research paper by Brian Wilkins.
South Island rivers are generally considered too cold for tubing. In the North Island, a cheap wetsuit should be worn at a minimum and spare inner tubes taken for floatation.
This page is a reproduction of the relevant section of FMC’s Safety in the Mountains booklet; first published in 1937, and still in print today, 11 editions later. You can buy your copy from the FMC website, at near giveaway price. More than 130,000 copies of this distilled mountain wisdom have found their way in to packs, huts and collections of generations of outdoors enthusiasts.