Related by context. Frequent words. (Click for all words.) 51 cenotes 46 freshwater lakes 46 karst 46 underwater caves 46 volcanic crater 45 mangrove swamps 45 tidal marsh 45 lagoons 45 coastal estuaries 44 landforms 44 intertidal 44 tidal marshes 44 seabeds 44 aquatic habitats 44 lava tube 43 rivers lakes 43 limestone caves 43 freshwater ecosystems 43 headwater streams 42 sinkholes 42 glacial lakes 42 retreating glaciers 42 toxic algae blooms 42 polluted rivers 42 Burgess Shale 42 freshwater wetlands 42 polluted waterways 42 ecosystems 42 rocky outcrops 42 wetlands 42 tidal pools 42 ecologies 42 estuaries 42 tailing ponds 41 biologically diverse 41 limestone cave 41 brackish waters 41 freshwater 41 tidal wetlands 41 streambeds 41 middens 41 salt domes 41 marine reptiles 41 brackish 41 geologic formations 41 salt crystals 41 rivers 41 reed beds 41 Elkhorn Slough 41 granite boulders 41 seagrasses 41 grottos 40 seepage 40 tributary 40 estuary 40 marshes 40 outcroppings 40 coastal wetlands 40 wetland habitats 40 wetland 40 lakes rivers 40 mud flats 40 Suisun Marsh 40 oxbow 40 ponds 40 contaminated sediments 40 streambed 40 biosphere reserve 39 sediment 39 waterways 39 geological formations 39 rock formations 39 diked 39 magma chamber 39 heavily polluted 39 waterfalls 39 geologic formation 39 fissures 39 caverns 39 Swamps 39 Dunkard Creek 39 Sinkholes 39 hydrological cycle 39 aquatic habitat 39 tidal creeks 39 rocky cliffs 39 waterholes 39 headwaters 39 sedimentation 39 lagoon 39 creeks rivers 39 marsh 38 overexploitation 38 wetland habitat 38 watersheds 38 marshland 38 headwater 38 sandstone cliffs 38 burrows 38 planktonic 38 navigable waterway