Why Hundreds of Barnacle-Encrusted Oil Tankers Remain Trapped After the Strait of Hormuz Ceasefire

The Strait of Hormuz is "open on paper," but a bizarre and multi-layered logjam is keeping over 600 oil tankers stuck in the Persian Gulf. Months of idling during the U.S.-Iran conflict have allowed dense marine growth — barnacles, mussels, and algae — to encrust hulls, rendering ships unseaworthy until cleaned. This problem is compounded by an active minefield, war-risk insurance premiums that have surged to as much as $8 million per transit, and a severe shortage of specialized hull-scraping divers. Analysts warn that full recovery of energy flows through the strait could stretch into late 2026 or beyond .

The Barnacle Crisis: Biofouling on a Massive Scale

Hundreds of vessels have been anchored in the warm waters of the Persian Gulf for over three months, providing a stable base for marine organisms to colonize. Each ship can accumulate up to 150,000 square feet of barnacles, mussels, clams, and algae — a phenomenon known as biofouling . A hull this encrusted drastically reduces fuel efficiency and speed, making the vessels unseaworthy until they are scraped clean . The problem is so severe that ports often ban barnacle-encrusted vessels from mooring, as the dense structures can damage port infrastructure and spread invasive species .

A 30-Fold Surge in Demand for "Bottom Cleaners"

The demand for specialist underwater hull-cleaning divers has skyrocketed. Since U.S. President Donald Trump announced the interim peace deal with Iran on June 14, orders for hull-cleaning crews have jumped more than 30-fold, according to Captain Manandeep Singh Kukreja, chief surveyor at Dubai-based Prominence Shipping Services LLC . This has created a unique "gold rush" for divers, with fees climbing from roughly $5,000 per ship to as much as $8,000 . The scramble is so intense that it is being called a "barnacle boom" . However, there are simply not enough qualified "bottom cleaners" to work through the backlog of over 600 vessels quickly .

The Minefield: 80 Naval Mines Still Block the Channel

Even if a tanker's hull is perfectly clean, the central shipping channel remains obstructed. The Guardian reports that approximately 80 naval mines are still blocking the main route, placed there since the conflict began on February 28 . Full clearance, involving minesweepers and state-of-the-art underwater drones, is expected to take 40 to 50 days . Until the channel is certified safe, most ship owners and their insurers refuse to transit, treating the strait as a war zone .

The Insurance Hurdle: War-Risk Premiums Make Transit Prohibitively Expensive

Insurance, not just mines, has effectively kept the strait closed. Before the conflict, war-risk insurance premiums were roughly 0.25% of a vessel's value. They have since surged to between 3% and 8% — which can add up to $8 million to the cost of a single tanker transit . One underwriter described the market as "quick to go up and slow to come down" . Insurers are taking a cautious "wait-and-see" approach, requiring weeks or months of sustained stability and verified mine clearance before they will lower premiums back to normal levels . This creates a vicious cycle: mines can't be cleared without insurance, and insurance won't come down until the mines are gone .

Logistical Gridlock and the Slow Return to Normal

Even when hulls are cleaned, mines are cleared, and insurance costs fall, the sheer volume of waiting vessels will create a massive traffic jam. With over 600 ships queued, analysts project that energy flows through the strait are unlikely to exceed half of prewar levels within the first month . A full recovery of shipping traffic is expected to stretch toward late 2026 or beyond, according to the most optimistic forecasts .

The Broader Impact on Global Energy Markets

The crisis has sent ripples through global energy markets. While crude oil prices initially fell below $80 per barrel following the ceasefire announcement, analysts caution that any price relief is "sentiment-driven rather than supply-driven" until the physical bottlenecks are resolved . The disruption has already pushed crude oil tanker rates to multi-year highs . The logjam at Hormuz, once resolved, will release a flood of pent-up oil supply, but the path to that resolution remains long and uncertain.