how many of these islands are still forming?

There are several islands around the world that are still actively forming due to volcanic activity and geological processes. Specifically:

1. In the Tonga region, a new island is still growing at Home Reef through ongoing volcanic eruptions that have expanded the island multiple times since 2022. The island's size increased as recently as early 2025 due to continuous lava flows and volcanic activity.
2. In the Galapagos Islands, two of the westernmost islands, Isabela and Fernandina, are still actively forming. Isabela, composed of six shield volcanoes, and Fernandina, with its active volcano La Cumbre, frequently experience eruptions that reshape and add new land.
3. New volcanic islands have also emerged recently in places like Japan near Iwo Jima (2023 eruption), and other newly created islands via volcanism can be found worldwide. Some volcanic islands remain stable while others continue to evolve with ongoing activity.

So, among notable island groups, at least two Galapagos islands and the newly formed islands in Tonga, Japan, and other volcanic hotspots are still actively forming and changing today.