The list of ship decommissionings in 1978 includes a chronological list of all ships decommissioned in 1978.
| Operator | Ship | Flag | Class and type | Fate | Other notes | ||
|---|---|---|---|---|---|---|---|
| 9 January | Finnlines | Finnhansa | ferry | Sold to Birka Line | Renamed Prisessan | ||
| February | La Traverse Nord-Sud Ltd | Manic | ferry | Sold to Kefalliniki Sa | Renamed Ainos | ||
| 13 March | Sessan Linjen | Fennia | ferry | End of charter, returned to Svea Line (Finland) | Laid up until April | ||
| 10 May | Polferries | Aallotar | ferry | End of charter from Effoa, purchased by Polferries | Renamed Rogalin | ||
| 28 July | [1] | ||||||
| 9 November | Aarhus-Oslo Linie | Peer Günt | ferry | Sold to Stena Line | Renamed Stena Baltica |