Water is not automatically a no-drone area in Latvia. You can often fly over a river, lake or the sea in the Open category, but the flight still has to pass the same legal checks as any other location.
Check airspace.lv/drones for the exact route. A lake shore, river bend, port area or coast can fall inside a UAS geographical zone. If the zone conditions require filing, use UASIS before take-off.
The hardest practical limit over water is VLOS. A drone that is easy to see over a field can become hard to judge over reflective water, haze or low sun. In the Open category you must keep the aircraft in visual line of sight; "I can see it on the screen" is not enough.
Also look below the flight path. Avoid people on boats, swimmers, animals and structures where possible. If the route crosses private property on the shore, keep the crossing short and choose the safest trajectory. In coastal wetlands and protected areas, nature rules may add a separate restriction.
Use the main Latvia flight-location hub, run a quick can I fly here check, and study the baseline rules in the A1/A3 course.
