What type of map shows contours connecting points of equal rainfall?

An isohyetal map is specifically designed to depict contours that connect points of equal rainfall over a specific area. By connecting these points, the map visually represents variations in precipitation, which helps to analyze rainfall patterns and distribution across different regions. This is particularly useful in fields such as hydrology, agriculture, and meteorology, as it allows for a better understanding of water resources and their management by visualizing how rainfall varies spatially.

Topographic maps, while they may show contours, focus primarily on elevation and landforms rather than precipitation data. Bathymetric maps are concerned with underwater features and contours of the ocean floor, which is unrelated to rainfall. Planimetric maps represent horizontal positions of features without any elevation or vertical data. Hence, the specificity of the isohyetal map to rainfall makes it the correct choice for the question about mapping contours of equal rainfall.