Question about oceans and land

Land masses change temperature much faster than oceans do, right?

What would life be like if land masses were slow to warm up and slow to cool down, but the temperature of ocean water fluctuated by about 70 degrees or so (say, 12 degrees in the winter and oh, 82 degrees in the summer)??

It would be a lot more pleasant in Minnesota in the wintertime, I can tell ya, ya betcha!