Here’s four of them:
The big ships offload to smaller tankers – a process called lightering.
Oddly enough, San Francisco’s inept SFMTA transit agency has spilled more petroleum into SF Bay than any single vessel spill over the past 40 years. We had the Cosco Busan mishap a few years back, but that was a container ship and it only spilled fuel it was going to use on its trip across the Pacific. The Bay Area has never had a big big oil tanker spill.
The 1971 SF Bay Oil Spill was as close as we came…