A ship is being bombarded by thunder, lightning and rain – in short – a tempest (surprise!) that seems worse than the big storm in King Lear.
Boat crewmembers try to keep everything afloat for their passengers, who are, as follows: Alonso (the King of Naples), Sebastian (the King's brother), Antonio (the Duke of Milan), Ferdinand (son of the King), and Gonzalo (an honest old councilor). Basically, it's a hubbub of courtly figures putzing around while the experienced sailors are trying to save everyone from drowning.
Drowning is likely in this storm, since the ship is described as "leaky as an unstaunched wench." (We dare you to look that up.)
The King and Prince take the advice of the sailors and go below deck to pray while Antonio, Sebastian, and Gonzalo stay above. Gonzalo has already exchanged words with the boatswain, who was testy to the royals. Antonio and Sebastian show their nasty dispositions, calling the boatswain an uncharitable dog and a whoreson.
While everyone's busy being friendly, the mariner demands that everyone should get busy and pray because "all's lost!"
Brain Snack: Shakespeare has always liked to insert a good shipwreck into his plays but the wreck in The Tempest may have been inspired by a real-life accident at sea. In 1609, the Sea Venture was on its way from England to Jamestown when it wrecked in the Bermudas. The crew was thought to be lost forever but managed to survive on an uninhabited island for about nine months – to everyone's shock and dismay, the crew built two new ships and sailed on to Jamestown. (Learn more about the Sea Venture shipwreck here.)