First and foremost is the depth of the water.
Today’s cruise ships have drafts (distance below the water) of
up to 33 feet. Think Royal Caribbean.
Container ships are much heavier (due to cargo rather than
vacationers) and have drafts up to 50 feet.
Then one must consider obstacles on the sea surface, such as
boat wrecks or just abandoned refrigerators. American shippers estimate an extra
6 feet for these obstacles. Russian sailors recommend 7 feet.
When I worked for hard money lenders, I sometimes had to
deal with jokers who pretended that their bays could be converted to world
class cruise ship ports or even cargo ship ports, with accompanying warehouses
or luxury resorts.
One particular memory was Guanica Bay, Puerto Rico. Read the
original blog post here:
https://www.internationalappraiser.com/search?q=puerto+rico
The gist of the story is that Guanica Bay had a depth of
only 29 feet, which was an obstacle to the larger cruise ships. Subtracting 7
feet reduces maximum draft to just 22 feet. The turbidity of the water,
furthermore, reduced the attractiveness of the proposed beach resort.
Cuba recently renovated its Mariel Bay (remember the Marielitos
emigration of 1980) at a cost of more than one billion dollars (financed by Brazil)
to create an internationally competitive port, so near the U.S., with a minimum
depth of 58 feet. A century ago this bay
had an average depth of less than 20 feet.
In summary, depth matters, water quality matters, and be
sure that all the required permits are in place, no matter what country you are
in.