Note that unlike the Santander ferry there are no seats on the upper deck. The stabilisers provide a very stable platform even in a sizeable swell. It is often hard to believe you are on a boat. Biscay can get very rough but this is less common in summer. Or to Hugh Harrop of the new cetacean organisation Orca.
Photographic evidence is also very useful.
Many sightings may not be identifiable to species. For example Andy Williams considers the beaked whales a very difficult group to identify accurately. If you do not have a GPS tracker the approximate location of sightings can be related to the course diagrams on the maps opposite the information desk on deck 6. It shows positions at 6 hourly intervals along the route. It also shows water depths.