The Greek adjective episphales (ἐπισφαλής) means dangerous, unsafe, precarious, slippery — literally "liable to stumble or fall." It appears only once in the NT in Acts 27:9, where Paul warns the crew that continuing the voyage would be episphales — dangerous and likely catastrophic. The word describes a situation fraught with existential peril.
Acts 27:9-10 captures one of the NT's clearest instances of prophetic practical wisdom: Paul, a prisoner with no navigational authority, reads the season (after the Day of Atonement, late in sailing season) and declares the voyage episphales. He is ignored. The storm comes. The ship is lost. Paul was right.
The theological takeaway is not simply "listen to the apostle on nautical matters" but the deeper truth that spiritual discernment illuminates practical danger. The same Spirit who gives prophecy also gives practical wisdom. Hebrews 6:19 describes hope as "an anchor for the soul, firm and secure" — the antithesis of episphales. The believer anchored to Christ has stability that the world's best navigational skills cannot provide.