Rivers, more than ravines, are the single deadliest killers in mountaineering in the Philippines. Not the flat, broad bodies of water that flow at a leisurely pace and dry up during summer at the country's few flood plains, but the smaller feeder streams that tumble at steep angles down narrow channels from its many mountain ranges. In the dry season the flows in some are reduced to a trickle, but with the onset of the southwest monsoons, when it rains for up to 24 days in a month and major ranges like the Cordilleras are regularly drenched with up to 1,200 millimeters, they become torrents, being the only outlets for all that excess water.

As pointed out to me by a club elder, river crossings have never been a formal part of our basic mountaineering course. We teach people to walk on vertical walls and to use their packs as rafts, but not this equally essential skill. I think it's about time we devoted more time to it, since we do almost all the training climbs during the wet season. There are a few rules of the thumb, but it is easy to forget them unless you yourself have experienced the terror of losing your footing and being swept downstream.

• Avoid narrow channels (they are invariably deep, because the water cannot cut through bedrock), and always cross at the widest possible section. Remember that existing trails do not automatically lead to the latter, since they are traversed mostly in the dry season.
• Avoid river bends especially on the outside, where the current is faster.
• Avoid sections deeper than your knees. Use trekking poles or sticks to measure the depth.
• Avoid V-shaped currents that form between two rocks or other obstacle that create a swift-flowing funnel effect.
• Avoid crossing directly upstream of large boulder fields, logs, or brush overhang that could trap or drown you if you lose your footing.
• Unfasten backpack waistbelts and sternum straps and loosen shoulder straps when crossing so you don't get dragged down by your pack if you lose your footing.
• Install rope aid where possible, and make cordage a mandatory item of group equipment.
• Cross as a team, ideally in threes, forming triangular anchors and holding onto the shoulder tops of your teammates.
• Cross diagonally, facing upstream.
• Tiny ripples indicate shallower waters and safer crossing points.
• The lee side of rocks are usually eddies of calm. Head for these spots when you have to stop and rest amidstream.
• When swept by the current, wriggle out of your pack and float on your back head held high, facing downstream with knees bent and toes up to avoid getting injured by underwater obstacles. Use your feet to kick off rocks for steering and head toward eddies or the near bank. Avoid fallen trees.