Encyclopedias, Almanacs, Transcripts, and Maps
- Seals and Sea Lions
- Sears, Paul Bigelow (1891 – 1990) American Ecologist and Conservationist
- Seasonal Ceremonies
- Seattle, Noah (1786 – 1866) Duwamish Chief
- Seaturtles (Cheloniidae)
- Secchi Disk
- Secernentea (Secernenteans)
- Second World
- Secondary Recovery Technique
- Secondary Standards
- Secret Societies
- Secretary Birds (Sagittariidae)
- Sediment Contamination
- Sedimentation
- Sedna
- Seebeck, Thomas Johann (1770–1831)
- Seed Bank
- Seedsnipes (Thinocoridae)
- Seepage
- Sefer Yetsirah