Missionaries not allowed to swim because Satan controls the water

False

It seems like all missionaries know that they should avoid water at all costs because Satan has more control over the water, but is this true.

The background for this myth comes from Doctrine and Covenants section 61:

On their return trip to Kirtland the Prophet and ten elders had traveled down the Missouri River in canoes. On the third day of the journey many dangers were experienced. Elder William W. Phelps, in daylight vision, saw the destroyer riding in power upon the face of the waters.

The following revelation was then received:

D&C 61:13-19

13 And now, behold, for your good I gave unto you a commandment concerning these things; and I, the Lord, will reason with you as with men in days of old. 14 Behold, I, the Lord, in the beginning blessed the waters; but in the last days, by the mouth of my servant John, I cursed the waters. 15 Wherefore, the days will come that no flesh shall be safe upon the waters. 16 And it shall be said in days to come that none is able to go up to the land of Zion upon the waters, but he that is upright in heart. 17 And, as I, the Lord, in the beginning cursed the land, even so in the last days have I blessed it, in its time, for the use of my saints, that they may partake the fatness thereof. 18 And now I give unto you a commandment that what I say unto one I say unto all, that you shall forewarn your brethren concerning these waters, that they come not in journeying upon them, lest their faith fail and they are caught in snares; 19 I, the Lord, have decreed, and the destroyer rideth upon the face thereof, and I revoke not the decree.

Note that the Lord specifies these waters. He does not say all water.

The connection between missionary policy and the reference to the “destroyer” riding the face of the waters in D&C 61 is a persistent Mormon urban legend. One must consider that LDS missionaries frequently travel by water to reach remote islands. Before the advent of modern air travel, all overseas missionaries were required to travel by ship to Europe, Asia, and other foreign lands. Missionaries, of course, bathe and perform baptisms in water.

The Church has a general policy prohibiting full-time missionaries from swimming. This is simply a safety precaution to prevent drowning or other water-related accidents. There are a number of other mission rules that vary depending upon the mission. For example, some missions prohibit missionaries from playing basketball or other physical sports. Rock climbing is usually a prohibited activity. Mission rules are designed to keep missionaries safe by preventing them from participating in high-risk physical activities.