Females are slightly bigger than the males and reach up to 2.5 meters in length and about 250 kg in weight.
So, they are significantly bigger than the Harbor Seal!
Actually they are active day and night. They have to eat nearly nonstop with that hyperactive metabolism (what I know is that they can survive only few hours without food). Last year in Europe my daughter was very lucky to make a video of presumably Southern water shrew (at ~1800-1900m above the see level) feeding on peace of apple dropped from a tourist. In the middle of the day! Unfortunately she had only her cellphone in hand...Nice shots of this cute and shy animals!
Good luck to see them in daylight, probably nocturnal animals.