In the top right corner of the map window is an overview map which shows the extent of the main map window.
Clicking on the '+' symbol in the top right of the overview map will expand the box to show a checklist of map features that can be turned on.
Many of the layers listed have extra information about the features on the map. If a layer that can be queried for further information is currently turned on, the mouse cursor will change to show a question mark, though this will vary depending on the type and setup of the computer or device you are using to view the website.
Clicking on a queryable feature will return further information recorded about that feature in a popup box, though not all features have extra details.
To see more of the map area the 'Search and Browse' panel can be hidden by clicking the button in its top right corner.