HMT Plethos
| Name | HMT Plethos |
| Type | Navy Trawler |
| GRT | 210 tons |
| Country |  British |
| Built | 1913 |
| Builder | A. Hall & Co. Ltd., Aberdeen |
| Operator | Royal Navy |
| History | Peace-time operator: East Coast Steam Fishing Co. Ltd., Aberdeen |
U-boat attacks on Navy Trawler Plethos
| Date | U-boat | Loss type | Position | Location | Route | Cargo | Casualties | |
| 1 | 23 Apr 1918 | U 80 (Karl Koopmann) | Sunk | Mined 40 miles E of Montrose, east Scotland | 4 | |||
| Mines laid on April 20, 1918. | ||||||||
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