Lens recommendations for watching whales

Ok, for my birthday tomorrow Sam has booked for us to go whale watching!!
I can't wait.
Has anyone been and does anyone have any lens recommendations? Obviously I'll take all I have, but I'm thinking longer lenses would be better?
I can just see me changing lenses right at the moment it breaches and I miss the shot of a lifetime.
Cheers

Has anyone been and does anyone have any lens recommendations? Obviously I'll take all I have, but I'm thinking longer lenses would be better?
I can just see me changing lenses right at the moment it breaches and I miss the shot of a lifetime.
Cheers