diff --git a/README.md b/README.md
index 96fdac5..a7d5e2a 100644
--- a/README.md
+++ b/README.md
@@ -20,6 +20,9 @@ Lein dependency:
 
     [walkmap "0.1.0-SNAPSHOT"]
 
+* [API documentation](https://simon-brooke.github.io/walkmap/codox/index.html)
+* [Test coverage](https://simon-brooke.github.io/walkmap/cloverage/index.html)
+
 ### Converting heightmaps to STL
 
 Doesn't work yet, and is not a priority. Use
@@ -74,6 +77,20 @@ from height maps. These exclusion maps will probably be represented as SVG.
 
 This is not yet implemented.
 
+Culling facets in ocean areas is implemented and works:
+
+    (require '[walkmap.core :refer [cull-ocean-facets *sea-level*]])
+    (cull-ocean-facets stl)
+
+If sea level in your heightmaps is not zero, e.g. is 5, set it thus:
+
+    (def ^:dynamic *sea-level* 5.0)
+    (cull-ocean-facets stl)
+
+It is **strongly recomended** that you set `*sea-level*` to a floating point
+number, not an integer, because numbers are specified in the STL file as
+floating point, and in Clojure, `(= 5 5.0)` returns `false`.
+
 ### Merging road maps and river system maps
 
 It is intended that it should be possible to merge road maps (maps of already
diff --git a/doc/intro.md b/doc/intro.md
index 3820a3f..d283148 100644
--- a/doc/intro.md
+++ b/doc/intro.md
@@ -16,6 +16,9 @@ Lein dependency:
 
     [walkmap "0.1.0-SNAPSHOT"]
 
+* [API documentation](https://simon-brooke.github.io/walkmap/codox/index.html)
+* [Test coverage](https://simon-brooke.github.io/walkmap/cloverage/index.html)
+
 ### Converting heightmaps to STL
 
 Doesn't work yet, and is not a priority. Use
@@ -70,6 +73,20 @@ from height maps. These exclusion maps will probably be represented as SVG.
 
 This is not yet implemented.
 
+Culling facets in ocean areas is implemented and works:
+
+    (require '[walkmap.core :refer [cull-ocean-facets *sea-level*]])
+    (cull-ocean-facets stl)
+
+If sea level in your heightmaps is not zero, e.g. is 5, set it thus:
+
+    (def ^:dynamic *sea-level* 5.0)
+    (cull-ocean-facets stl)
+
+It is **strongly recomended** that you set `*sea-level*` to a floating point
+number, not an integer, because numbers are specified in the STL file as
+floating point, and in Clojure, `(= 5 5.0)` returns `false`.
+
 ### Merging road maps and river system maps
 
 It is intended that it should be possible to merge road maps (maps of already