A jungle gateway rather than a family destination: heat, insects and long boat rides, which some children take to completely and others do not.
The bridge to San Buenaventura
The road bridge over the Beni replaced the old boat crossing and gives you a free, flat walk over a very large river, with the town on one side and La Paz department on the other. Ten minutes each way, and the best free thing to do here with a small child.
The boat is the main event
Everything upriver is reached by long motor canoe, and for most children the journey turns out to be better than the destination. Hats, long sleeves and water: there is no shade in the middle of a river.
Pampas rather than jungle, with young children
The Yacuma pampas trips involve far less walking and much more animal-watching from a boat, while the Madidi jungle trips mean real hiking in heat and humidity. With under-tens, the pampas is the easier of the two by a distance.
Heat, sun and insects
This is 200m above sea level and properly tropical, so the risks with children are heat and sunburn rather than altitude. Repellent, long sleeves at dusk and a hat matter more than anything else in the bag, and December to March is the wettest, hardest stretch.
The town itself is small
A few thousand people, a handful of streets and a plaza; there is very little in the way of built attractions to work through. Treat the town as where children rest between trips rather than as somewhere to entertain them.