Read the paragraph and assign which is the topic sentence?

The waves increased in height throughout the afternoon until I was unable to see shore when my little sail boat dropped into the trough between two of them. The wind was constantly changing direction, making it hard for me to control the direction of my boat. Often the gusts were so strong that they blew the crests from the tops of the waves, soaking me in a salty mist. If I were to capsize, there were no boats around to help me. I realized that I had picked the worst day of the year to teach myself to sail a boat.