Any Seaplane or Floatplane (same thing), be it a Cessna Caravan or a large multi engine flying boat is limited by wave height, and water condition. No matter what any overly eager salesman may suggest to you, all seaplanes are restricted in what capacity they can safely operate. The only way to properly determine this is to have a professional who is experienced in the particular aircraft you are considering come and do a proper site or operational study of the area you are planning on using. It is quite normal for anyone to assume that since an aircraft has floats on it, they can safely and easily land it in the middle of the ocean, or even out in a large lake. The fact is, we rarely ever land in the middle of any large body of water. Waves and swells from whatever source are normally too large to safely allow that. Occasionally it can be done, but we would never make a flight plan to expect to go and do that.
There is a Hollywood fantasy that since someone has achieved the prestigious position of a 747 Captain, or any jet pilot for that matter, that they somehow are an expert on every other lesser, or smaller aircraft. This may be true in Hollywood but not in the real world. I have taught hundreds of seaplane pilots from every aviation background, from Lufthansa to United Airlines to Japan Airlines and Thai Airways, and these big airplane fellows are sometimes the most difficult to train. Not because they are not skilled and talented individuals, but because they do not have the feel for a lighter aircraft, and the experience and judgment to assess the water landing area which is an ever changing sloppy unpredictable runway. They can and do learn the art very well, but it often takes them a bit longer to adjust to the very different feel of a seaplane.
Boating Captains and Sailors without any formal Seaplane training, although they may have the best intentions are not generally a good source to judge what is a safe or proper landing and takeoff area for a seaplane. Their skills are many and diverse but seaplanes are a tricky business and often don't precisely follow the rules of the mariner. Once we are on the water we legally become a boat and must follow those rules, but in the air and when we are assessing a landing area and touching down at very high speeds we have a completely different view of a completely different situation than someone on the water. Working together with Yacht Captains which I have done many times to arrange pickups and drop offs needs to be thoroughly discussed and planned and works well once we have worked out safe and specific docking procedures.
Civil Aviation Authorities and Employment Departments around the world would like new Seaplane Operators to train their pilots to be Seaplane Pilots. Unfortunately this has not worked well in many countries so far due to a few reasons. First, most young pilots didn't grow up wanting to be Seaplane Pilots. They would prefer being seen walking through a terminal dressed in their sharp blue uniforms rather than be seen swimming like Tarzan through an alligator infested river with a rope in their mouths trying to save their seaplane from damage. Also, most investors would prefer a paying passenger in the right seat rather than the dead weight of a short term co-pilot. The right way for a Seaplane Pilot to be born is to go through the school of hard knocks and really find out if it is "What they really enjoy". This can take three or four years to really get the experience to know if it is right for an individual. It simply does not happen in three or four months.
Building docks and ramps for seaplanes must be done by experienced seaplane operators. Docks and rafts that may be good for boats are often completely unacceptable for seaplanes. Seaplanes are light and built with thin aluminum and cannot take very much pounding from any object. Don't expect your seaplane to pull up to any dock or raft anywhere anytime without prior assessment. The romantic photo of the seaplane pulling up to the remote beach is actually rarely done for many reasons although it can be a safe and fun thing to do.
It takes two aircraft which is really a minimum for any commercial service. A new Caravan Amphibian EX runs about 3.0million + usd completely outfitted and flown to your location. Spare parts, tooling and support equipment will run about half a million or much more if you must build or refurbish a hanger. Concrete ramps and docks must also be considered. Using second hand aircraft can of course lower the initial outlay, but each new project has unforeseen circumstances which need good solid financial resources in place. Single ownership for business or private use is of course a completely different situation.
People starting seaplane businesses normally hire Pilots before they hire an Engineer. This is putting the cart before the horse. Not long ago airplanes were not so complicated and an average fellow could keep them running, but things have changed dramatically and a good Engineer can demand just about anything he wants nowadays. If aircraft are not repaired properly pilots will not stay around while a junior engineering student experiments with a new toy. One correct decision by an experienced fellow can mean your aircraft flies that day and you make money without spending a dime in repairs. One wrong decision on the same problem can mean you are pulling out your credit card and ordering an expensive electronic module for 82,000usd that won't even fix the aircraft, and you also have lost many thousands of dollars in revenue.
Today's complex Engineering Decisions can make or break you. Good Pilots will follow when you have Good Engineers in your flight department.
Seaplane service to hotels, boats and remote landing areas is a great efficient way to travel and good entertainment for all when it is properly planned and safely executed. It can be pleasant for the community when it is done by professionals who know how to avoid boating and recreational water and beach hazards, and who can be responsible with a fine machine with a sometimes noisy turbine engine. But correct planning and experienced people are the key. Good luck with your new seaplane venture!