Will be visiting in March, looking for recommendations for good nature walks, ocean walks, things like that. Thank you!
+1 for Caw Caw
Magnolia Plantation on the Ashley River. Half-hour drive from downtown. Entry fees are a la carte - skip the house, skip everything except general admission and maybe the Audubon Swamp.
For a full day, drive nearly an hour to the Bulls Island Ferry and spend the day on an uninhabited sea island.
There are nature trails at the local county parks: James Island and Palmetto Isles Parks are both nice and have very inexpensive admission. There's also Charlestowne Landing State Park in West Ashley that is historic with exhibits, besides having nature trails., but is more expensive to get in.