Which of the following factors may influence estimated time of arrival (ETA)?

The estimated time of arrival (ETA) is significantly influenced by factors such as weather conditions and tides. Weather impacts navigation through various elements like winds, currents, waves, and visibility. For instance, strong headwinds can slow a vessel down, while favorable winds can increase speed. Similarly, tides can affect a vessel's route; high tides may allow for smoother passage in shallow areas, whereas low tides may require slower navigation or avoidance altogether. These combined effects can lead to a substantial variation in travel time, making weather and tides critical considerations in calculating ETA.

While other factors like the type of vessel, traffic conditions in seawater, and the availability of navigational aids do play roles in overall navigation and safety, they do not have as direct an impact on the ETA as weather and tides do, which alter both speed and route choices in real-time conditions on the water. Thus, emphasizing how vital weather and tide considerations are for accurate ETA predictions.