New York City has the chance to overcome its isolation from the North American goods-movement system - and regain a significant role in maritime affairs - by pursuing innovative technological strategies.

New York City's Staten Island holds the key to a future boom in its cargo handling. Why Staten Island? It boasts direct road and rail access from the city to the rest of the country, most of which is located on the west side of the Hudson River.The harbor can be readied for the coming century by pursuing radical new infrastructure development:

* At a strategic point on Staten Island, New York City can develop and build a caisson-jetty, a pier-like structure of prefabricated modules, for mega-container ships. (Other caisson jetties could be built in Brooklyn for motor vehicles and even robotic trucks.)

* Meanwhile, for long-term protection, we should begin construction at the mouth of the harbor of an extensive, gated coastal seawall system to shield the entire New York-New Jersey region against sea rise.

To implement these innovations, the city must first extend railroad tracks on Staten Island to the Verrazano-Narrows Bridge at the mouth of New York Harbor. There they would connect with a caisson-jetty that would jut seaward into the open waters of Lower New York Bay along the west bank of Ambrose Channel.

The jetty - its rectangular modules, partially buoyed by hydrostatic pressure, built with tracks inside or atop them - would provide deck and lower-level space for marine-terminal activities. That would include containership berths and container cranes. Containers would be moved between land and ship along the jetty.

The new jetty terminal would allow the huge, deep-draft container vessels already coming on line to tie up at the entrance to the harbor. They would not have to wend their way miles through the upper bay and the narrow Kill Van Kull into Newark Bay, where the majority of the harbor's container-ship facilities are currently located. Expensive new dredging along that route would not be necessary.

Once a new generation of high-capacity gantry cranes was lofting containers on and off ships at the caisson-jetty, New York would be able to celebrate the first economically viable maritime facility in Lower New York Bay.

Moreover, aside from jetties for Staten Island, caisson construction could be used for multi-level - even underwater - waterfront development in Brooklyn.

The novel construction approach would improve traffic circulation. In fact, a sub-aqueous caisson structure could replace Brooklyn's infamously traffic-clogged Gowanus Expressway. The float-in structural elements could either replace the elevated Gowanus or bypass the catastrophic gridlock that would ensue from landside Gowanus reconstruction.

The tunnel also could anchor a futuristic highway complex suitable for the introduction of robotic freight movement to the metropolitan area. The complex would include the tunnel, connector ramps and roadways, and the Verrazano-Narrows Bridge. Robo-trucks and cyber-trailers on power-distributing guideways could move along dedicated lanes through the new complex.

Meanwhile, the region faces a dire natural threat. A bold approach, combined with an old material, can help protect it.

Climatologists agree that the ocean, which has already risen one foot in the 20th century, will rise at least three feet more in the 21st. And when ocean water pours into an estuarial harbor like New York's, hundreds of miles of waterfront are flooded.

But an extensive sea-wall system, built of garbage, could protect the region and indeed the East and Gulf Coasts. The mountains of urban waste generated by New York and other large cities could be processed and used to create the walls to protect against surf and sea. Cassion-jetties could be used to get the processed garbage to the construction sites.

New York produces more tons of waste than any other commodity, and sea rise is a fact of life. (The Dutch have been building sea walls for hundreds of years, though they haven't had our volumes of garbage to help them.)

To prevent disastrous flooding of coastal areas, and so ships can pass through the great sea walls, ports will need ''gates'' that can be opened to admit ships, or closed to prevent tidal and storm surges from inundating ports and estuaries. Such structures will prove critical to our future as the sea rises.

Fixed port facilities have a life of as much as a century. It is not too early for the maritime community to look for a long-term approach to the potentially limiting relationship of ship size and port facilities in the coming century.

As ship size surges and the ports of the world increase their defensive structures against imminent sea rise, compatibility of vessel and port becomes even more crucial to the survival of port facilities in New York and New Jersey - and elsewhere.

Saving the world's port cities from a rising sea with seawalls and gates - while maintaining vital maritime commerce - would prove the final hurdle in completing what we call the ''sea walls of Earth,'' a 21st-century infrastructure project likely to be counted among the most mammoth and significant public works undertakings in history.