Session 1 is your landmark row. You could consider splitting this up into two rows with a short break in between to give you time to stretch, hydrate and eat if required.
Session 2 is a shorter session, and a different format again. This week sees the introduction of longer intervals, with short recovery time, requiring you to focus on pacing in each row.
|4 x 3km
Session 3 is your cross training session. The modality is up to you, but it should be something that keeps your heart rate slightly raised for the duration of the session.