diff --git a/gliderpy/__init__.py b/gliderpy/__init__.py
index 37971ac..8d2cbf0 100644
--- a/gliderpy/__init__.py
+++ b/gliderpy/__init__.py
@@ -4,3 +4,11 @@
     from ._version import __version__
 except ImportError:
     __version__ = "unknown"
+
+from .fetchers import GliderDataFetcher
+from .plotting import plot_transect
+
+__all__ = [
+    "GliderDataFetcher",
+    "plot_transect",
+]
diff --git a/gliderpy/fetchers.py b/gliderpy/fetchers.py
index 2c5326d..009d915 100644
--- a/gliderpy/fetchers.py
+++ b/gliderpy/fetchers.py
@@ -16,6 +16,7 @@
 )
 
 OptionalBool = bool | None
+OptionalDF = pd.DataFrame | None
 OptionalDict = dict | None
 OptionalList = list[str] | tuple[str] | None
 OptionalStr = str | None
@@ -80,7 +81,7 @@ def __init__(
         )
         self.fetcher.variables = server_vars[server]
         self.fetcher.dataset_id: OptionalStr = None
-        self.datasets: OptionalBool = None
+        self.datasets: OptionalDF = None
 
     def to_pandas(self: "GliderDataFetcher") -> pd.DataFrame:
         """Return data from the server as a pandas dataframe.
@@ -97,10 +98,7 @@ def to_pandas(self: "GliderDataFetcher") -> pd.DataFrame:
             self.fetcher.dataset_id = None
             return glider_df
         else:
-            msg = (
-                f"Must provide a {self.fetcher.dataset_id} or "
-                "`query` terms to download data."
-            )
+            msg = "Must provide a dataset_id or query terms to download data."
             raise ValueError(msg)
 
         # Standardize variable names for the single dataset_id.
@@ -145,7 +143,7 @@ def query(  # noqa: PLR0913
             "longitude>=": min_lon,
             "longitude<=": max_lon,
         }
-        if not self.datasets:
+        if self.datasets is None:
             url = self.fetcher.get_search_url(
                 search_for="glider",
                 response="csv",
diff --git a/gliderpy/plotting.py b/gliderpy/plotting.py
new file mode 100644
index 0000000..d1e5d33
--- /dev/null
+++ b/gliderpy/plotting.py
@@ -0,0 +1,57 @@
+"""Some convenience functions to help visualize glider data."""
+
+from __future__ import annotations
+
+import warnings
+from typing import TYPE_CHECKING
+
+try:
+    import matplotlib.dates as mdates
+    import matplotlib.pyplot as plt
+except ModuleNotFoundError:
+    warnings.warn(
+        "gliderpy requires matplotlib and cartopy for plotting.",
+        stacklevel=1,
+    )
+    raise
+
+
+if TYPE_CHECKING:
+    import pandas as pd
+
+from pandas_flavor import register_dataframe_method
+
+
+@register_dataframe_method
+def plot_transect(
+    df: pd.DataFrame,
+    var: str,
+    **kw: dict,
+) -> tuple(plt.Figure, plt.Axes):
+    """Make a scatter plot of depth vs time coloured by a user defined
+    variable.
+
+    :param var: variable to colour the scatter plot
+    :return: figure, axes
+    """
+    cmap = kw.get("cmap", None)
+
+    fig, ax = plt.subplots(figsize=(17, 2))
+    cs = ax.scatter(
+        df.index,
+        df["pressure"],
+        s=15,
+        c=df[var],
+        marker="o",
+        edgecolor="none",
+        cmap=cmap,
+    )
+
+    ax.invert_yaxis()
+    xfmt = mdates.DateFormatter("%H:%Mh\n%d-%b")
+    ax.xaxis.set_major_formatter(xfmt)
+
+    cbar = fig.colorbar(cs, orientation="vertical", extend="both")
+    cbar.ax.set_ylabel(var)
+    ax.set_ylabel("pressure")
+    return fig, ax