diff --git a/worldeditadditions/init.lua b/worldeditadditions/init.lua
index a7c10f8..e96fa9f 100644
--- a/worldeditadditions/init.lua
+++ b/worldeditadditions/init.lua
@@ -18,6 +18,7 @@ dofile(worldeditadditions.modpath.."/utils/raycast_adv.lua") -- For the farwand
 dofile(worldeditadditions.modpath.."/lib/floodfill.lua")
 dofile(worldeditadditions.modpath.."/lib/overlay.lua")
 dofile(worldeditadditions.modpath.."/lib/layers.lua")
+dofile(worldeditadditions.modpath.."/lib/fillcaves.lua")
 dofile(worldeditadditions.modpath.."/lib/ellipsoid.lua")
 dofile(worldeditadditions.modpath.."/lib/torus.lua")
 dofile(worldeditadditions.modpath.."/lib/walls.lua")
diff --git a/worldeditadditions/lib/fillcaves.lua b/worldeditadditions/lib/fillcaves.lua
new file mode 100644
index 0000000..debb983
--- /dev/null
+++ b/worldeditadditions/lib/fillcaves.lua
@@ -0,0 +1,55 @@
+--- Overlap command. Places a specified node on top of each column.
+-- @module worldeditadditions.overlay
+
+function worldeditadditions.fillcaves(pos1, pos2, node_name)
+	pos1, pos2 = worldedit.sort_pos(pos1, pos2)
+	-- pos2 will always have the highest co-ordinates now
+	
+	-- Fetch the nodes in the specified area
+	local manip, area = worldedit.manip_helpers.init(pos1, pos2)
+	local data = manip:get_data()
+	
+	local node_id_replace = minetest.get_content_id(node_name)
+	local node_id_ignore = minetest.get_content_id("ignore")
+	
+	-- minetest.log("action", "pos1: " .. worldeditadditions.vector.tostring(pos1))
+	-- minetest.log("action", "pos2: " .. worldeditadditions.vector.tostring(pos2))
+	
+	-- z y x is the preferred loop order, but that isn't really possible here
+	
+	local changes = { replaced = 0 }
+	for z = pos2.z, pos1.z, -1 do
+		for x = pos2.x, pos1.x, -1 do
+			local is_first_node_in_col = true
+			local prev_is_air = false
+			local found_toplayer = false
+			
+			for y = pos2.y, pos1.y, -1 do
+				local i = area:index(x, y, z)
+				
+				local is_air = worldeditadditions.is_airlike(data[i])
+				local is_ignore = data[i] == node_id_ignore
+				
+				-- If the previous node was air and this one isn't, then we've found the top level
+				if prev_is_air and not is_air then
+					found_toplayer = true
+				elseif is_first_node_in_col and not is_air then
+					found_toplayer = true
+				elseif found_toplayer and is_air and not is_ignore then
+					-- We've found the top layer already and this node is air,
+					-- so we should fill it in
+					data[i] = node_id_replace
+					changes.replaced = changes.replaced + 1
+				end
+				
+				is_first_node_in_col = false
+				prev_is_air = is_air
+			end
+		end
+	end
+	
+	-- Save the modified nodes back to disk & return
+	worldedit.manip_helpers.finish(manip, data)
+	
+	return true, changes
+end
diff --git a/worldeditadditions_commands/commands/fillcaves.lua b/worldeditadditions_commands/commands/fillcaves.lua
new file mode 100644
index 0000000..3a764a7
--- /dev/null
+++ b/worldeditadditions_commands/commands/fillcaves.lua
@@ -0,0 +1,36 @@
+-- ███████ ██ ██      ██       ██████  █████  ██    ██ ███████ ███████
+-- ██      ██ ██      ██      ██      ██   ██ ██    ██ ██      ██
+-- █████   ██ ██      ██      ██      ███████ ██    ██ █████   ███████
+-- ██      ██ ██      ██      ██      ██   ██  ██  ██  ██           ██
+-- ██      ██ ███████ ███████  ██████ ██   ██   ████   ███████ ███████
+worldedit.register_command("fillcaves", {
+	params = "[<node_name>]",
+	description = "Fills in all airlike nodes beneath the first non-airlike node detected in each column.",
+	privs = { worldedit = true },
+	require_pos = 2,
+	parse = function (params_text)
+		if params_text == "" then
+			params_text = "stone"
+		end
+		local replace_node = worldedit.normalize_nodename(params_text)
+		if not replace_node then
+			return false, "Error: Invalid node name."
+		end
+		
+		return true, replace_node
+	end,
+	nodes_needed = function(name)
+		return worldedit.volume(worldedit.pos1[name], worldedit.pos2[name])
+	end,
+	func = function(name, replace_node)
+		local start_time = worldeditadditions.get_ms_time()
+		
+		local success, stats = worldeditadditions.fillcaves(worldedit.pos1[name], worldedit.pos2[name], replace_node)
+		if not success then return success, stats end
+		
+		local time_taken = worldeditadditions.get_ms_time() - start_time
+		
+		minetest.log("action", name .. " used //fillcaves at " .. worldeditadditions.vector.tostring(worldedit.pos1[name]) .. ", replacing " .. stats.replaced .. " nodes in " .. time_taken .. "s")
+		return true, stats.replaced .. " nodes replaced in " .. worldeditadditions.human_time(time_taken)
+	end
+})
diff --git a/worldeditadditions_commands/init.lua b/worldeditadditions_commands/init.lua
index 229f460..0c7d879 100644
--- a/worldeditadditions_commands/init.lua
+++ b/worldeditadditions_commands/init.lua
@@ -24,6 +24,7 @@ dofile(we_c.modpath.."/many.lua")
 dofile(we_c.modpath.."/commands/floodfill.lua")
 dofile(we_c.modpath.."/commands/overlay.lua")
 dofile(we_c.modpath.."/commands/layers.lua")
+dofile(we_c.modpath.."/commands/fillcaves.lua")
 dofile(we_c.modpath.."/commands/ellipsoid.lua")
 dofile(we_c.modpath.."/commands/torus.lua")
 dofile(we_c.modpath.."/commands/walls.lua")