Remove Your Backpack
If you topple with it strapped to your back, the pack will force your torso and head underwater, so unbuckle the waist and sternum straps. If the water is up to your waist or above, wrap your pack in a waterproof bag, and either push or tow it across the river. Yes, it will float.
Hang on to Your Sleeping Pad
This is probably your most buoyant gear. Partially inflate the pad, then roll it up, and make arm loops from the compression straps so it can be your emergency PFD as you wade or swim; this also leaves your hands free for poles. Foam pads also work.
Make Water Wings
Link two or more empty plastic water bottles or bladders together with straps to create a chain of buoys.
Use Your Trousers
Remove your pants, tie off the cuffs, grasp the open waistband, and plunge it top first into the water to fill the legs with air. The Red Cross teaches this when no better options exist. Note: Even Bear Grylls had trouble crossing a lake with only his pants keeping him afloat (he had to re-inflate them midway).
Choose Your Route
Wider or braided channels signal slower, shallower water. Face the current at a 45-degree angle and carry poles or sticks. If walking across, wear shoes sans socks for traction. If swimming, go barefoot; sodden boots will drag you down.
Bright-yellow bags are more visible in low light and at night than black or red ones. Unfurl and wave them to signal airborne rescuers.