Neptune as God of the Sea rides a shell-shaped chariot and is followed by three blonde haired nereids, the sound of a conch shell bugle signally his arrival.

The winds are personified as faces in the clouds above him, and behind Neptune is a fleet of ships. These ships represent the fleet that carried Ferdinand in 1633, which sailed from Barcelona on its voyage to the city of Genoa. On the way, the fleet ran into a terrible storm that forced the fleet to dock into the safe haven of the Codaques harbour.

Neptune Calming the Tempest uses many tools that are common to the genre of Baroque. The painting conjures up the chaos brought on by the tossing and turning of the sea in a storm, with the three faces of the winds, Auster, Zephyr and Boreas, blow the storm clouds onwards, whilst the sea churns below Neptune's chariot, his white hair and beard whipped up by the frenzy.

The white foam of the sea is depicted as cantering horses under Neptune's command, and even the blowing of the conch shell gives a great depth of sound as well as movement to the painting. The sails of the ships and the direction of the waves gives the painting an intense feeling of forward motion that carries the viewer along with it.

Another popular theme in Baroque painting was allegory, which again is evident in Neptune Calming the Tempest. Rubens returns to using classical Roman mythology and literature to mirror the journey of Ferdinand with Virgil's Aeneid. In the Aeneid, Neptune was able to assure safe passage for Aeneid by placating the rough winds that were threating his ships, and again the parallel is seen here in Rubens depiction of the Ferdinand's fleet too.

The contrasting colours give this painting great depth, with the dark swirling sea in the foreground, the calm blue skies and wispy white clouds lining the horizon in the distance. The painting Neptune Calming the Tempest was commissioned by the magistrates of Antwerp, following on from Rubens many other successful commissions. In fact, Ferdinand was the nephew of Archduchess Isabella, another one of Rubens previous commissions, and the painting was composed in order to welcome Ferdinand to Antwerp, Belgium in 1635.