Why bother
Most of Prague's iconic views are designed to be seen from a bridge or a hilltop — a boat trip flips that, putting you at river level looking up at Charles Bridge's arches and the castle rising behind Malá Strana. It's a genuinely different angle on a city you might feel you've already seen from every other vantage point.
Short sightseeing cruises
The most common option is a short loop, roughly 45 minutes to an hour, passing under Charles Bridge and around the small islands near the National Theatre before heading back. These run frequently through the day and don't need advance planning in most cases.
Dinner and evening cruises
Longer dinner cruises run in the evening, combining a meal with the same river views, now lit up after dark. These are a step up in price and formality, and worth booking ahead if you have a specific evening in mind — treat it as a special-occasion option rather than the default way to see the river.
Is it worth it?
If your time in Prague is short, this sits below the castle, the bridge and the Old Town Square on the priority list — but if you have a spare hour, particularly in the late afternoon light, it's a relaxing way to see the same landmarks from a new angle without any walking involved.