I own a place in Garden City Beach SC that sits in a gated community .8 miles from the ocean. There is a 10 acre tide fed saltwater pond. No boating/swimming/basically don't touch the water. We can fish. Redfish 25-35 lbs are somewhat common. Big Flounder too. How can I figure out where the deeper holes are?

Google Earth and zoom down. Works well for IDing deeper water on some of our local lakes/ponds.

They used to make a cast-able depth finder I believe

Otherwise kayak at night with a depth finder and just map it out real quick

just fish it