It may end up as the longest river in continental Europe, but the Danube starts small at a spring in the heart of the small Black Forest town of Donaueschingen, and doesn’t become navigable until the city of Ulm, a distance of roughly 200km. Accordingly this first stretch of stripling waterway does not figure widely in tour operator brochures, which tend to focus on big river cruises, and yet it is one of the prettiest waterside routes in Germany, ideal for cycling.

Donaueschingen is a handsome little place, and its celebrated Danube (Donau) spring bubbles out of the ground between the town’s palace and its brewery. These days it has been railed in to make a little pool surrounded with balustrades which tourists treat as a wishing well, throwing coins into the water.

After just 20 km it vanishes completely

Shadowed by the cycle route which goes all the way to Budapest, the river sets off full of hope, initially through parkland and water meadows, but then after just 20 km it vanishes completely near the village of Immendingen into an underground system of watercourses, leaving behind a weedy, puddled riverbed which only really flows during seasons of heavy rain and melting snow.

Fortunately this weedy bed is slowly refilled by tributaries, and then for the next 30 kilometres the re-born river wanders mazily through lovely pastoral landscape of fruit orchards and cattle grazing, burrowing through a limestone gorge in the southernmost skirts of the Swabian Alb. A lot of the riverbank land hereabouts is owned by the very prosperous Benedictine abbey at Beuron, with its fabulously decorated baroque church, and abbey produce – particularly meat – on sale in abbey shops.

Beuron is the first of several major abbeys that line the river, and the next town, Sigmaringen, is the setting for its first major castle, a Hohenzollern property stuck dramatically up on a riverside rock, where the Nazi-controlled French Vichy government was incarcerated during the Second World War.

At the next, very pretty, town of Riedlingen, whose main square is lined with ancient, slightly wonky, half-timbered and gabled houses, there’s a choice of routes: sticking to the river for the straight run into Ulm, or diverting up the Ach valley to the resort town of Blaubeuren, where the river Blau emerges dramatically from a giant hole in the ground.

The Blau meets the Danube at Ulm, the first big city on the Danube, whose cathedral has the tallest church spire in Europe at 161 metres. From Ulm downriver there are more castles, monasteries and notable cities, but now that the river is navigable, mainstream tourism kicks in. Upstream of Ulm a river-following cyclist is in his or her own world; below Ulm, he or she will begin to meet up with others, and then from Passau, to blend with the crowds.

Plenty of organisations (see our Tour Operator pages) offer packages along the Danube Cyclepath (Donau Radweg), but route finding is a doddle, and there are plenty of bike-friendly guest houses, so it is just as easy to organise it yourself. A handy guide is The Danube Cycleway, published by Cicerone.

Andrew Eames’s book about travelling the Danube, Blue River Black Sea, is available from Amazon.