As you read this, Bali’s most impressive volcanic mountain, Gunung Agung, continues to threaten a full-scale eruption that would produce vast pyroclastic flows, a huge stratospheric pillar of sky-borne ash, and many tonnes of basaltic rocks flung into the air – all potentially affecting millions. If Agung’s current rumbling becomes a full-scale eruption, vast landscapes across the island and well beyond will be affected. It could even wreak havoc on global weather patterns and agriculture, just as Mt Tambora did, back in 1815. If Gunung Agung’s current dyspepsia becomes a full eruption, international air travel might well be strangled throughout Asia and well beyond for weeks – or even months. J. BROOKS SPECTOR remembers a more peaceful time high up on that very mountain, and the surprising result of that trip.