Pack light, fellow divers, because the airlines are
cutting their luggage limits, and if you’re flying coach,
you’re going to pay. Exceed the limits and you will be
shipping your gear separately. And, that 60 lb. carryon
is also a thing of the past.
  Continental’s weight allowance starting
  September will be 70 lb./ checked bag, either
  domestic or international. They’ll collect a $25
  fee for checked bags 51–70 lbs. And they’ll
  accept no bag weighing more than 70 lbs.,
  even if it’s carrying your Light & Motion
  housing. That’s right, no exception for sports
  equipment. Items weighing more than 70 lbs. must be
  sent in advance via a known shipper or freight forwarder.
  These arrangements can’t be made at the gate when
  you’re told your bag’s over the limit.
Continental’s weight allowance starting
  September will be 70 lb./ checked bag, either
  domestic or international. They’ll collect a $25
  fee for checked bags 51–70 lbs. And they’ll
  accept no bag weighing more than 70 lbs.,
  even if it’s carrying your Light & Motion
  housing. That’s right, no exception for sports
  equipment. Items weighing more than 70 lbs. must be
  sent in advance via a known shipper or freight forwarder.
  These arrangements can’t be made at the gate when
  you’re told your bag’s over the limit.  
International allowances for size and weight will
  vary by destination, carrier, and — in some cases — by
  class. For example, Singapore Airlines will allow two
  checked pieces weighing 70 lb. each, but frequent flyers
  and first- and business-class passengers can check
  more. TACA limits you to 100 lbs. total, with a maximum
  of 70 lbs. for one bag. Carry-ons are also limited
  by weight (about 45 pounds in most cases) as well as
  size.  
On domestic flights, Delta will sock you $25 each
  way for a bag weighing 51–70 lbs, while United, on
  domestic and Caribbean flights, makes it $50. It’s $100
  each way if a bag weighs 71–100 lb. and major airlines
  won’t accept a bag weighing more. American Airlines
  spokesman Tim Wagner warned Undercurrent that divers
  who can’t get a piece of luggage below 100 lbs. “won’t
  be taking that bag with them.”  
More restrictions are coming from nearly every carrier.
  Do your homework on their Web sites, by phone
  or with your travel agent. Before you leave, weigh your
  bags on your bathroom scale. Go for soft-sided luggage.
  Buy books at your destination. Rent a BC. Forget that
  hair dryer. Live in one T-shirt, shorts and flip-flops. Ask
  a buddy to tote some of your load. Get creative. Or fly
  business class.