The island, with a sandy beach known as Dollymount Strand running its entire length, is a relatively recent, and inadvertent, result of human intervention in the bay.

After years of primitive dredging, an attempt to maintain a clear channel more effectively was begun when, in 1715, the first piles were driven of what was to become the Great South Wall, completed in 1730.

This barrier was breached by storm action some years later, and in 1761, a stone pier was commenced, working from the Poolbeg Lighthouse (1768), back to shore, the construction of massive granite blocks being completed in 1795.

Captain William Bligh, of Bounty fame, surveyed Dublin Bay for the Ballast Board in 1801, highlighting the potential of the North Bull sandbank.

Over the succeeding 48 years, the natural tidal effects created by the walls deepened the entry to the Liffey from 1.8 m to 4.8 m. Much of the silt now scoured from the river course was deposited on the North Bull, and a true island began to emerge, with people venturing out to the growing beach.

In addition to picnics and swimming, the island was used for shooting practice, and in 1880, an international rifle match between Ireland and the USA was held there, with an audience numbering several thousand.

Sometime in the early 20th century, a track suitable for walking and handcarts, running from a slipway at the point where the Howth Road comes from Raheny's village centre down to the coast, was formed.

The Royal Dublin Golf Club clubhouse was used as officers' quarters and considerable damage was done to the building and, particularly due to trench warfare practice, the island environment as a whole.

Called the "Blue Lagoon Scheme," this would have included dams and sluices at the Wooden Bridge and Sutton Channel, maintaining a high water level behind the island, which itself might hold some housing or tourism facilities.

On the northern side of the Bull, between the island and the mainland, is a large linear saltmarsh complex backed by mudflats all of which are covered at high tide.

A wide range of birds visit Bull Island, with a more limited set nesting there; most are either winter feeders, or pass through in spring and autumn.

Species include the pygmy shrew, brown rat, red fox, field mouse, hedgehog, European rabbit and Irish hare,[5] the latter having become extinct between 2016 and 2019, while the stoat has been observed since the mid-2010s.

Hares, which are believed to have populated the island from the farmlands of Raheny and Kilbarrack, were very common up until the 1960s, but the building of the causeway led to a reduction in their numbers due to disturbance.

During a study of hares on the island during the 1990s, it was concluded that poor breeding success due to disturbance from people and, more seriously, dogs, was the main cause of the drop-off in numbers.

[7] The island is also home to ground beetles, various species of butterflies and moths, aphids, wasps, snails, spiders and harvestmen, earthworms and woodlice.

The walking of dogs is also popular, though they are supposed to be kept under control, due to the National Nature Reserve status, and in particular to fears of attacks on rabbits and hares.

For about two decades, access by car was limited to a portion of the island near the Bull Bridge and two sections reached from the causeway at Raheny, the latter having ceased in 2016.

[10] In July 2021, Dublin City Council demolished one of Simms' lifeguard stations dating from 1934 without notice, citing ongoing issues with anti-social behaviour at the abandoned structure.

[13] Water quality continues to be affected by several issues, including lack of capacity of existing sewage treatment facilities, excess nutrients flowing into Dublin Bay from the River Liffey and other watercourses, and stormwater pollution.