| Term: | Friendly ice |
| Definition: | From the point of view of the submariner, an icy canopy containing many large ice skylights or other features which permit a submarine to surface; there must be more than ten such features per 37 kilometers (30 nautical miles) along the submarine's track. |
| Term: | Friendly ice |
| Definition: | Sea ice terminology that describes an ice canopy containing many large skylights or other features, which permits a submarine to surface. There must be more than 10 such features per 30 nautical miles (56 km) along the submarine's track. |
| Term: | Friendly ice |
| Definition: | From the point of view of the submariner, an ice canopy containing many large skylights or other features that permit a submarine to surface. There must be more than ten such features per 30 n mi (56 km) along the submarine's track. |
| Term: | Friendly ice |
| Definition: | From the point of view of the submariner, an ice canopy containing many large skylights or other features that permit a submarine to surface. There must be more than 10 such features per 56 km (30 nautical miles) along the submarine's track. |
| Term: | Friendly ice |
| Definition: | From the point of view of the submariner, an ice canopy containing many large ice skylights or other features which permit a submarine to surface. There must be more than ten such features per 30 nautical miles along the submarine's track. |