diff --git a/nav.py b/nav.py
index 025c9f6..17a25c1 100644
--- a/nav.py
+++ b/nav.py
@@ -15,6 +15,7 @@ DISTANCES = {
     ("gateway", "venus"): 41.0,
     ("mars", "phobos"): 0.01,
     ("mars", "deimos"): 0.02,
+    ("venus", "mercury"): 50.0,
 }
 
 # Every route starts at Earth.
@@ -24,6 +25,7 @@ ROUTES = {
     "venus": ["earth", "gateway", "venus"],
     "phobos": ["earth", "gateway", "mars", "phobos"],
     "deimos": ["earth", "gateway", "mars", "deimos"],
+    "mercury": ["earth", "gateway", "venus", "mercury"],
 }
 
 NAMES = {
@@ -34,6 +36,7 @@ NAMES = {
     "venus": "Venus",
     "phobos": "Phobos",
     "deimos": "Deimos",
+    "mercury": "Mercury",
 }
 
 CRUISE_SPEED = 0.87  # million km per day