The Atlantic Maritime Ecozone constitutes a cluster of peninsulas and islands which form the northeastern end of the Appalachian mountain chain that runs from Newfoundland to Alabama. The highest point, Mount Carleton in New Brunswick, reaches 807 metres and offers a magnificent view. In the uplands, repeated glaciation has produced shallow, stony soils, and outcrops composed of granite, gneiss, and other hard, crystalline rocks. Rough upland terrain and poor soils are often unsuitable for farming and have discouraged extensive settlement. The inhospitable highlands feature cold, wet climates and acidic soils, but yield vast forests.

Coastal lowlands of the Northumberland Plain accommodate the greater share of the population and agricultural activities. Here, deeper soils are traced to marine deposition and glacial erosion of underlying sandstone, shale, and limestone bedrock. With the exception of P.E.I., abrupt transitions between uplands and lowland basins mark much of the ecozone's landscape. The majority of the ecozone is overlaid by nutrient-poor Podzol soil and better-quality grey-brown Luvisol soils.

Numerous lakes speckle rugged regions of igneous rock, such as volcanics and granite, which are covered by a thin layer of soil. Rivers and streams predominate in areas of sedimentary bedrock and thicker soils. Over 11 000 kilometres of coastline are deeply indented by tidal inlets and impressive sand dunes. Almost 4 000 offshore islands dotted with lagoons and extensive marshes ring Nova Scotia. Red sandstone cliffs and hard volcanic rocks in the Bay of Fundy tower over intertidal beaches up to 5 kilometres wide.

The proximity of the Atlantic ocean creates a moderate, cool, and moist maritime climate. Most of the ecozone experiences long, mild winters (averaging about -4°C in January) and cool summers (the mean daily July temperature is 18°C). Coastal communities are generally several degrees warmer in winter and slightly cooler in summer.

During late spring and early summer, the mixing of the cold Labrador Current and the warm Gulf Stream produces frequent banks of sea fog over coastal areas. Average precipitation varies from 1 000 mm inland to 1 425 mm along the coast. The average annual growing season ranges from 1 500 to over 1 750 growing degree days above 5°C. Frost-free days, on average, fluctuate from 80 in the New Brunswick highlands to 180 along the coast. With a storm frequency higher than anywhere else in Canada, sunshine can be a rare commodity.