Depends where in the world you are. Around Japan, sure. Anywhere near the BuOrd testing ranges though and you'll get an explosion ending for the year.
The magnetic detonators themselves worked quite well, the problem was that the Earth's magnetic field is not consistent the world over and the technology available at the time wasn't sensitive enough to detect the variance. The settings used were enough to detonate the torps on the test ranges but all the volcanism and geological activity in the west Pacific threw off the sensors enough to cause a failure, hence the back and forth between the BuOrd and the submariners.
Well, assuming we're working at scale here (i.e. a torpedo small enough to be carried around by one person as it is in the image), the magnetic detonator wouldn't really be in factor unless it went under the bell or there was some huge metal structure just above those ropes. In this case we're just looking at the contact detonator, which at that lovely perpendicular impact angle the Mark 14 had right around a 100% failure rate.
Well, assuming we're working at scale here (i.e. a torpedo small enough to be carried around by one person as it is in the image), the magnetic detonator wouldn't really be in factor unless it went under the bell