The far East end and far West end of Galveston Island are especially dangerous areas to swim. On the Eastern tip of the Island, the bottom drops off rapidly into the Houston-Galveston Ship Channel, averaging 50ft deep. The wake from passing ships can cause sudden currents and breakers that can catch swimmers off guard.

While Galveston's beaches are generally safe, you should avoid swimming in areas under active bacteria advisories or near storm drains and industrial zones. The Galveston County Health District and Texas Beach Watch regularly monitor water for Enterococcus bacteria; if levels exceed safe standards, advisories are posted both on the beach and online. You should also be cautious about swimming in the Galveston Ship Channel or near the Texas City Dike, as these areas have heavy industrial traffic and unpredictable currents. Additionally, swimming near the rock groins (jetties) along the Seawall can be dangerous due to barnacles that cause deep cuts and the presence of rip currents that pull swimmers toward the rocks. For those with open wounds or compromised immune systems, the naturally occurring Vibrio vulnificus ("flesh-eating") bacteria is a rare but serious concern in warm, brackish water; such individuals are advised to avoid swimming during the peak summer months or immediately after heavy rainfall when runoff levels are highest.