The design of the PortMiami Tunnel (PMT) utilizes segmental reinforced concrete lining panels. Early corrosion initiation is expected to be mitigated by the specification of low permeability ternary-blend concrete and minimum three-inch clear cover, but there is uncertainty in the long-term corrosion and materials durability (particularly considering its ambitious 150 year design life) and uncertainty of the extent of possible loss of concrete integrity of the structure at extended times. Therefore, interest lies in continual long term corrosion monitoring of the tunnel panels. The objectives of this testing program are to provide information on the panels that may indicate possible early corrosion development in key areas of the tunnel and to provide field data to supplement laboratory testing to provide recommendations for best practices addressing corrosion prevention and mitigation for submerged structures. The findings from corrosion monitoring for over 10 years of service are presented.