diff --git a/server/src/atlas/region_profile.rs b/server/src/atlas/region_profile.rs
index a2befac71..0d1c88d08 100644
--- a/server/src/atlas/region_profile.rs
+++ b/server/src/atlas/region_profile.rs
@@ -133,7 +133,11 @@ pub enum VegetationClass {
 /// only — see `derive_temperature_c`.
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 pub struct BodyParams {
-    /// `bodies.hydrosphere` — "ocean" | "ice" | "rivers" | "none" | "subsurface" | NULL
+    /// `bodies.hydrosphere` — the real vocabulary in systems.db: "ice",
+    /// "liquid_water", "none", "rivers", "moderate", "ocean", "minimal", "trace",
+    /// "subsurface_liquid", "rivers-lakes", "extensive", "subsurface_ice",
+    /// "subsurface", "ocean-coastal" | NULL. The `[hydrosphere_maritime]` table
+    /// keys on these for temperature moderation (D-240).
     pub hydrosphere: Option<String>,
     /// `bodies.atmosphere` — "breathable" | "thin" | "toxic" | "none" | "dense" | NULL
     pub atmosphere: Option<String>,
@@ -1359,21 +1363,27 @@ mod tests {
                     // Sweep sea level AND high altitude so the lapse term + clamp
                     // are exercised jointly against the cold end, not just lat alone.
                     for elev in [0.0_f64, 6.0] {
-                        for seed in seeds {
-                            let params = BodyParams {
-                                planet_class: Some((*class).into()),
-                                atmosphere: Some((*atmo).into()),
-                                region_latitude_deg: lat,
-                                elevation_km: elev,
-                                ..Default::default()
-                            };
-                            let t = derive_temperature_c(&params, &climate, seed)
-                                .expect("non-airless body must have temperature");
-                            assert!(
-                                t >= cold && t <= warm,
-                                "class={class} atmo={atmo} lat={lat} elev={elev} seed={seed}: \
-                                 temperature {t}°C outside band [{cold}, {warm}]"
-                            );
+                        // Sweep hydrosphere too, so the maritime-compressed gradient
+                        // path is covered by the band invariant (not just None/1.0).
+                        for hydro in ["none", "ocean", "liquid_water", "rivers", "ice"] {
+                            for seed in seeds {
+                                let params = BodyParams {
+                                    planet_class: Some((*class).into()),
+                                    atmosphere: Some((*atmo).into()),
+                                    hydrosphere: Some(hydro.into()),
+                                    region_latitude_deg: lat,
+                                    elevation_km: elev,
+                                    ..Default::default()
+                                };
+                                let t = derive_temperature_c(&params, &climate, seed)
+                                    .expect("non-airless body must have temperature");
+                                assert!(
+                                    t >= cold && t <= warm,
+                                    "class={class} atmo={atmo} hydro={hydro} lat={lat} \
+                                     elev={elev} seed={seed}: temperature {t}°C outside \
+                                     band [{cold}, {warm}]"
+                                );
+                            }
                         }
                     }
                 }