diff --git a/.gitmodules b/.gitmodules
index 0f73951ea..e69de29bb 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,13 +0,0 @@
-[submodule "ext/tug"]
-	path = ext/tug
-	url = ../tug.git
-
-[submodule "ext/iphreeqc"]
-	path = ext/iphreeqc
-	url = ../iphreeqc.git
-[submodule "ext/ai-surroagate"]
-	path = ext/ai-surroagate
-	url = git@git.gfz-potsdam.de:naaice/ai-surrogate-poet.git
-[submodule "ext/ai-benchmarks-utils"]
-	path = ext/ai-benchmarks-utils
-	url = git@git.gfz-potsdam.de:naaice/ai-benchmarks-utils.git
diff --git a/ext/ai-surroagate b/ext/ai-surroagate
deleted file mode 160000
index 1a2dfc6a4..000000000
--- a/ext/ai-surroagate
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 1a2dfc6a48fb82b86d142c297db539315d135797