Complex sentence: The next day, two Spanish climbers, Pepe Garces and Lorenzo Ortas (not Lorenzo Ortíz, who was killed in the storm), who had survived the storm at Camp 4, were descending the mountain suffering from frostbite and exhaustion.
Split into simpler sentences: The next day, two Spanish climbers, Pepe Garces and Lorenzo Ortas (not Lorenzo Ortíz, who was killed in the storm), were descending the mountain. They had survived the storm at Camp 4, but were suffering from frostbite and exhaustion.