diff --git a/virtual_ship/instruments/__init__.py b/virtual_ship/instruments/__init__.py
index 261bd7a8..f6d89a5a 100644
--- a/virtual_ship/instruments/__init__.py
+++ b/virtual_ship/instruments/__init__.py
@@ -1,6 +1,6 @@
 """Measurement instrument that can be used with Parcels."""
 
-from . import argo_float, drifter
+from . import argo_float, ctd, drifter
 from .location import Location
 
-__all__ = ["Location", "argo_float", "drifter"]
+__all__ = ["Location", "argo_float", "ctd", "drifter"]