Mike's absolutely correct that there will be plenty of opportunities for close-ups well composed and well exposed when you land. But I would not forsake the opportunities of shots from the boat. The seals, of course, but also shots of cliffs covered in birds and if you're lucky birds in flight from sea level - especially good if you get birds taking off within range (http://www.birdforum.net/gallery/showphoto.php/photo/254276/ppuser/6605). Just remember to take plenty of memory cards and spare batteries.
Bill
Bill