Phylum: Red algae (Rhodophyta)
| Site | Municipality (county) | Num. obs. | Num. species | Num. images | Last obs. | |
|---|
| Sand-Mulvika | Vestfold, Norway | 43 | 1 | 0 | 2001-09-18 | |
| Sandeid | Rogaland, Norway | 18 | 1 | 0 | 1996-10-08 | |
| Sandeåsen | Vestfold, Norway | 15 | 1 | 0 | 1997-10-09 | |
| Sandholna | Vestland, Norway | 8 | 3 | 6 | 2019-05-24 | |
| Sandvika | Rogaland, Norway | 27 | 1 | 0 | 1999-09-29 | |
| Sandvika | Finnmark, Norway | 5 | 1 | 0 | 1994-10-04 | |
| Sandøy | Møre og Romsdal, Norway | 6 | 1 | 0 | 1995-10-17 | |
| Sandå-Skarestrand | Agder, Norway | 24 | 1 | 0 | 1995-09-21 | |
| Saura | Nordland, Norway | 13 | 1 | 0 | 1995-10-03 | |
| Selje | Vestland, Norway | 22 | 1 | 0 | 1995-09-21 | |
| Senjahopen | Troms, Norway | 2 | 1 | 0 | 1995-03-17 | |
| Senjahopen | Troms, Norway | 2 | 1 | 0 | 1993-11-15 | |
| Sigerfjord | Nordland, Norway | 5 | 1 | 0 | 1995-09-29 | |
| Sirevåg-Ogna-Varden | Rogaland, Norway | 10 | 1 | 0 | 1996-09-26 | |
| Skarbo | Telemark, Norway | 1 | 1 | 0 | 1994-12-05 | |
| Skattval | Trøndelag, Norway | 3 | 2 | 2 | 2020-06-10 | |
| Skaug | Nordland, Norway | 1 | 1 | 0 | 1994-11-29 | |
| Skinnfelltangen | Agder, Norway | 5 | 1 | 0 | 1993-09-16 | |
| Skjebergkilen | Østfold, Norway | 12 | 1 | 0 | 1995-09-25 | |
| Skjellvika | Vestfold, Norway | 4 | 1 | 0 | 1993-09-17 | |
| Skjernøya | Agder, Norway | 28 | 1 | 0 | 1995-09-21 | |
| Skogerøya | Agder, Norway | 32 | 1 | 0 | 1997-10-02 | |
| Skogsområde | Vestland, Norway | 3 | 1 | 0 | 2005-10-19 | |
| Skottevig | Agder, Norway | 13 | 1 | 0 | 1995-10-09 | |
| Skottevik | Agder, Norway | 1 | 1 | 1 | 2013-09-12 | |
| Skånevik | Vestland, Norway | 20 | 1 | 0 | 1996-10-04 | |
| Skåraneset | Rogaland, Norway | 12 | 1 | 0 | 1995-10-02 | |
| Slagen | Vestfold, Norway | 44 | 1 | 0 | 1997-09-25 | |
| Slemmestad | Akershus, Norway | 7 | 1 | 0 | 1996-09-16 | |
| Småvågane | Rogaland, Norway | 2 | 1 | 0 | 2016-06-10 | |
| Sola | Rogaland, Norway | 1 | 1 | 0 | 1995-09-08 | |
| Solastranda og Ølberg | Rogaland, Norway | 9 | 1 | 0 | 2004-06-11 | |
| Songebukta | Agder, Norway | 5 | 1 | 0 | 1994-12-05 | |
| Sortland | Nordland, Norway | 8 | 1 | 0 | 1996-10-02 | |
| Spervik | Vestfold, Norway | 28 | 1 | 0 | 1997-10-09 | |
| Spildepollen | Vestland, Norway | 2 | 1 | 0 | 1996-10-18 | |
| Spildra | Nordland, Norway | 4 | 1 | 0 | 1998-10-07 | |
| Stangodden | Agder, Norway | 15 | 1 | 0 | 1993-10-17 | |
| Stathelle | Telemark, Norway | 5 | 1 | 0 | 1998-09-23 | |
| Statland | Trøndelag, Norway | 24 | 1 | 0 | 1996-06-19 | |
| Stavern | Vestfold, Norway | 1 | 1 | 1 | 2023-08-03 | |
| Stavern | Vestfold, Norway | 27 | 1 | 0 | 1998-09-23 | |
| Stavern | Vestfold, Norway | 29 | 1 | 0 | 1999-09-29 | |
| Stavern | Vestfold, Norway | 21 | 1 | 0 | 2000-12-13 | |
| Steika | Vestfold, Norway | 14 | 1 | 0 | 1997-09-16 | |
| Steinsvikstranda | Møre og Romsdal, Norway | 11 | 1 | 0 | 1996-09-25 | |
| Stengelvåg | Nordland, Norway | 6 | 1 | 0 | 1995-06-08 | |
| Stokkastrand | Rogaland, Norway | 4 | 1 | 0 | 1995-10-03 | |
| Stord | Vestland, Norway | 1 | 1 | 0 | 1993-08-31 | |
| Stordammen | Akershus, Norway | 1 | 1 | 0 | 1989-09-27 | |
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