diff --git a/.readthedocs.yml b/.readthedocs.yml
index c3cfa3e57..f27933517 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -22,3 +22,5 @@ python:
   install:
     - method: pip
       path: .
+      extra_requirements:
+        - docs
diff --git a/docs/conf.py b/docs/conf.py
index 2064a0d9d..1a465806e 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -183,6 +183,7 @@ def _reset_ultraplot(gallery_conf, fname):
     "sphinxext.custom_roles",  # local extension
     "sphinx_automodapi.automodapi",  # fork of automodapi
     "sphinx_rtd_light_dark",  # use custom theme
+    "sphinx_sitemap",
     "sphinx_copybutton",  # add copy button to code
     "_ext.notoc",
     "nbsphinx",  # parse rst books
@@ -373,6 +374,8 @@ def _reset_ultraplot(gallery_conf, fname):
 # The name of the Pygments (syntax highlighting) style to use.
 # The light-dark theme toggler overloads this, but set default anyway
 pygments_style = "none"
+html_baseurl = "https://ultraplot.readthedocs.io/stable"
+sitemap_url_scheme = "{link}"
 
 
 # -- Options for HTML output -------------------------------------------------
diff --git a/docs/contributing.rst b/docs/contributing.rst
index e1aa270f6..ad4cb00c5 100644
--- a/docs/contributing.rst
+++ b/docs/contributing.rst
@@ -87,6 +87,7 @@ To build the documentation locally, use the following commands:
    cd docs
    # Install dependencies to the base conda environment..
    conda env update -f environment.yml
+   pip install -e ".[docs]"
    # ...or create a new conda environment
    # conda env create -n ultraplot-dev --file docs/environment.yml
    # source activate ultraplot-dev
diff --git a/environment.yml b/environment.yml
index 904673230..a9d9fe4f2 100644
--- a/environment.yml
+++ b/environment.yml
@@ -5,6 +5,7 @@ dependencies:
   - python>=3.10,<3.14
   - numpy
   - matplotlib>=3.9
+  - basemap >=1.4.1
   - cartopy
   - xarray
   - seaborn
@@ -13,25 +14,10 @@ dependencies:
   - pytest-mpl
   - pytest-cov
   - pytest-xdist
-  - jupyter
   - pip
   - pint
-  - sphinx
-  - sphinx-gallery
-  - nbsphinx
-  - jupytext
-  - sphinx-copybutton
-  - sphinx-autoapi
-  - sphinx-automodapi
-  - sphinx-rtd-theme
-  - typing-extensions
-  - basemap >=1.4.1
   - pre-commit
-  - sphinx-design
   - networkx
   - pyarrow
   - cftime
-  - m2r2
-  - lxml-html-clean
   - pip:
-      - git+https://github.com/ultraplot/UltraTheme.git
diff --git a/pyproject.toml b/pyproject.toml
index 9872f5853..6e20a36eb 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -57,3 +57,22 @@ ignore = ["I001", "I002", "I003", "I004"]
 
 [tool.basedpyright]
 exclude = ["**/*.ipynb"]
+
+[project.optional-dependencies]
+docs = [
+    "jupyter",
+    "jupytext",
+    "lxml-html-clean",
+    "m2r2",
+    "mpltern",
+    "nbsphinx",
+    "sphinx",
+    "sphinx-autoapi",
+    "sphinx-automodapi",
+    "sphinx-copybutton",
+    "sphinx-design",
+    "sphinx-gallery",
+    "sphinx-rtd-light-dark @ git+https://github.com/ultraplot/UltraTheme.git",
+    "sphinx-sitemap",
+    "typing-extensions"
+]