The town is situated on the slopes of Kaikohe Hill, a breached scoria cone set on a roughly circular shaped plateau formed by lava flows. Before the volcanic eruptions, the land was uplifted from the sea and subsequently suffered deep weathering from the actions of wind, rain, sun and the volcanic upheavals.
At Kaikohe the younger Taheke basalts, derived from eruptions, spread out on top of the older Horeke basalts.
Around Kaikohe the volcanic past can still be seen: basalt rock is visible, weathered as if it were limestone. (How this happened remains a mystery). Nearby are the Ngawha Hot Springs, still bubbling, boiling and steaming. The Ngawha geothermal power station, built in 1997and extended in 2006, is the only geothermal power station in Northland.
Just north of Kaikohe stands the smooth dome of Putahi, a hill of volcanic origins that is also a sacred burial place. Putahi was formed by hydrothermal activity extrusions and its dome has extinct steam vents that are still open.