1. Mosquitoes in the summer - hella bad since you're near the water.
2. Hella COLD in the winter with all that arctic air blowing off the water.
3. Living in Hawaii? Dangerously high surf in the winter time where your house could literally be washed off its foundation, and the ever present really real danger of Tsunamis. The last one (From the Japan Earthquake) did tens of millions of dollars in damage to a lot of homes.