Rashi: A river of fire and sulfur breached its normal flow, and inundated Sedom and Amorah.

Malbim: This is another way that precious metals are revealed. Gold is found in rocks of rivers, or mixed with sand under the river and its place is hidden. Sometimes the river reveals it - it breaches from its flow and flows elsewhere.

Rashi: These are Anshei Sedom, who made forgotten passersby through their land. They made guests lie down on a bed - if he was too tall, they cut off his legs. If he was too short, they stretched him (Sanhedrin 109b).

Malbim: There is gold there that was forgotten by those who sought gold and did not know about it, for the river flowed there. Now that it breached its boundary, the places hidden from man were raised to the dry land.

Rashi: Via the breaching of this river, it was lifted from people going through.

Ibn Ezra: They became desolate from passersby. Dalu is like Dalelu (destroyed).