Mainit Bubbles

A named site with historical specimen records

Gosliner’s 2011 taxonomic paper records specimens from Mainit Bubbles collected in May 2009 at 12 m. That provides a named historical locality; the collection depth is not a maximum depth or a standard dive profile.

Bubbling sand and a deeper wall

Michael McFadyen’s account, describing visits in 2023 and 2025, describes bubbles and warm water emerging from sand, followed by a wall section around 22–30 m. This is an account of his route, rather than evidence that every Mainit Bubbles outing covers those depths.

What remains uncertain

The observed bubbles do not by themselves establish the exact gas composition, origin or present activity. This guide does not carry forward the earlier precise geological explanation or suggest touching the vents. Confirm the intended section and current conditions with the operator. Historical specimens and a diver’s photographs do not establish present wildlife residency or encounter frequencies.

Wall habitat and the return slope

Michael McFadyen’s account of visits in 2023 and 2025 describes gorgonians, sponges and sea whips on the wall. He recounts returning up a sandy slope and across the reef top toward the boat. This adds detail about his route beyond the bubbling sand; it does not establish today’s boat position, itinerary or conditions.

Reading the visits and photographs separately

McFadyen explains that his camera battery was flat during the first 2023 dive and that photographs were added after two return dives in 2025. The page therefore combines recollections and later images. A photograph on it should not automatically be labelled as an image of the first visit, and the illustrated animals do not establish a continuous resident population.

Subjects beyond the bubbling sand

The written route reports nudibranchs, a yellow-spotted boxfish, a banded sea snake, shrimps and anemones with clownfish. These observations help distinguish the wall outing from a visit focused only on the bubbling area. They are historical reports, not a reason to assume that a booking includes every habitat or that a particular animal can be found on request.

The account describes anchoring in about 9 m before moving down the slope, then reaching the reef top around 20 m on the return and gradually ascending toward the boat. These are stages of one described itinerary. They do not establish a fixed boat position, a shallow-only route or a new site-wide minimum depth.

Visibility varied across the visits

The author reports 28°C water in August and October, with visibility ranging from roughly 5 m in the shallows to about 10–12 m across another dive and nearly 20 m on the wall during one visit. The differences matter when comparing a shallow photography outing with a deeper wall itinerary. They describe a small set of visits, not dependable seasonal ranges.