diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..3f8c24f
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "geographiclib"]
+	path = geographiclib
+	url = https://github.com/geographiclib/geographiclib.git
diff --git a/CMakeLists.txt b/CMakeLists.txt
index dcbc625..0b80ce8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,13 @@ cmake_minimum_required(VERSION 3.13)
 
 option(BUILD_FOR_PICO "Build for Raspberry Pi Pico" ON)
 
+set(GEOGRAPHICLIB_DIR ${CMAKE_CURRENT_SOURCE_DIR}/geographiclib)
 
+# Configure GeographicLib before adding it, to skip docs/tools/tests
+set(GEOGRAPHICLIB_LIB_TYPE "STATIC" CACHE STRING "" FORCE)
+set(BUILD_DOCUMENTATION OFF CACHE BOOL "" FORCE)
+set(BUILD_BOTH_LIBRARIES OFF CACHE BOOL "" FORCE)
+set(PACKAGE_DEBIAN OFF CACHE BOOL "" FORCE)
 
 if(BUILD_FOR_PICO)
     set(PICO_BOARD pico_w CACHE STRING "Board type")
@@ -14,6 +20,9 @@ if(BUILD_FOR_PICO)
 
     pico_sdk_init()
 
+    add_subdirectory(${GEOGRAPHICLIB_DIR} EXCLUDE_FROM_ALL)
+    target_compile_options(GeographicLib PUBLIC -fexceptions -frtti)
+
     add_executable(p-rad
         src/main.cpp
         src/core/logic.cpp
@@ -22,7 +31,7 @@ if(BUILD_FOR_PICO)
 
     target_compile_definitions(p-rad PRIVATE PICO_BUILD)
     target_include_directories(p-rad PRIVATE src)
-    target_link_libraries(p-rad pico_stdlib pico_cyw43_arch_lwip_threadsafe_background hardware_rtc)
+    target_link_libraries(p-rad pico_stdlib pico_cyw43_arch_lwip_threadsafe_background hardware_rtc GeographicLib)
 
     pico_enable_stdio_usb(p-rad 1)
     pico_enable_stdio_uart(p-rad 0)
@@ -34,6 +43,8 @@ else()
     set(CMAKE_CXX_STANDARD 23)
     set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
+    add_subdirectory(${GEOGRAPHICLIB_DIR} EXCLUDE_FROM_ALL)
+
     add_executable(p-rad
         src/main.cpp
         src/core/logic.cpp
@@ -44,5 +55,5 @@ else()
     find_package(Threads REQUIRED)
     find_package(SDL3 REQUIRED CONFIG)
     find_package(CURL REQUIRED)
-    target_link_libraries(p-rad Threads::Threads SDL3::SDL3 CURL::libcurl)
+    target_link_libraries(p-rad Threads::Threads SDL3::SDL3 CURL::libcurl GeographicLib)
 endif()
\ No newline at end of file