2 Chronicles 20:36

And he joined himself with him to make ships to go to Tarshish: and they made the ships in Ezion–geber.

Cross-reference

2 Chronicles 8:17 identifies Ezion-geber as Solomon's port, the same location where Jehoshaphat built his ill-fated ships.

1 Kings 9:26 notes Solomon built ships at the same location, Ezion Geber, showing Jehoshaphat reused that port.

1 Kings 22:49 shows Jehoshaphat declining Ahaziah's offer, contradicting the alliance described here.