Cozumel is Mexico's largest island and is located about 14 miles Southwest of the Yucatan Peninsula, 35 miles south of Cancun.   Cozumel is part of the Mayan Riveria (originally called the Cancun - Tulum corridor, but was renamed to the Riviera Maya in 1999).  

Most of Cozumel's development has taken place on the western side of the where there are 4 cruise ports.  The first was International Pier, built in the 1980s and home to Royal Caribbean Cruise Lines.   The second was built in 1998 at Puerta Maya and mainly supports Carnaval and NCL.  The shops at Puerta Maya are 3/4 mile walk South from the International Pier walkway.

The other 2 piers are nearly 3 miles North in San Miguel (2.4 miles to Punta Langosta, and 2.8 miles to the Ferry Pier).

The last of the Forum shops -- the most popular shopping area and where the taxis drop you off when you go "downtown" from International Pier (unless you tell the driver otherwise) -- are 3 miles away.  Be wary of misleading information from TripAdvisor, Cruise Critic and most other popular websites which perpetuate the myth that it's only a "20 minute walk" or 3 minute taxi ride.  While it might be technically accurate that the nearest dwellings in San Miguel are that close, it's certainly not where the action is nor where 98%+ of tourists travelling to San Miguel want to be.

A few comments on travelling to Cozumel.   The powerful taxi union has totally monopolized all island transportation for many years, even to the extent of denying local residents any form of public transportation until recently.   The taxi union is so strong that hotels are still prohibited from providing free airport shuttles.  

Taxis are the only form of transportation allowed at the cruise terminals, although a new water taxi service is scheduled to begin Fall of 2014 (much to the dismay of the Taxi Union which strongly disapproves).

While most shops and people are very laid-back and honest, travelers should be very wary of the Cozumel Car Rental Agencies.  A brand name car rental agency such as Thrifty or Herz means nothing.