Not content with destroying enough energy to power the world for 10 years, the Aceh explosion also revealed a new weapon, being explored by the PLA among others.
A small primer charge, set off in any deep feature of the seabed will ignite the clathrates present. The potent explosion will have little direct effect except on shorelines, experienced as a tsunami, probably of far lesser height than that at Aceh in most cases, but it depends on the extent of the seabed feature. The more intersting effect will be the instant and massive expansion from solid to gas, expanding even more as it inevitably travels towards the surface of the ocean.
Surface vessels are very unstable as flying machines. A CVN floating even momentarily in gas will lose orientation and assume a stern down posture. It is also likely to slip to one side or another or even turn to present the stem to the sky. It is unlikely to resume a survivable conformation when the sea replaces the gases liberated from the seabed explosion. It will sink intoi the sea and will likely disappear in minutes permanently. The effect on submarines will merely be to kill crew, unless securely strapped into beds or seating.
Detonation should be timed for the presence of the major target over the likely area of gas expansion.
A variant of thios is the nuclear mine, built to withstand immense pressure and set off on the deep sea bed a few minutes before the target is overhead. The steam bubbles formed will also sink the fleet vessels so caught. Radiation damage will be slight. This will be detected by the target vessels possibly as a tectonic event, earthquake or undersea volcano.
I would advise adopting maximum speed and 60 degree course change, if nearby geography permits for 5 minutes or so if any tectonic events are encountered while at sea.