All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
First of all, you should know that swimming is not permissible in swimming pools where men and women freely intermix or ‘Awrahs (parts of the body that must be covered in Islam) are uncovered. If the swimming pool is exclusive to men and ‘Awrahs are not likely to be uncovered, it is permissible for you to go there. For further information, see Fataawa 84712 and 84231.
In principle, the earth surface is pure. The Prophet, sallallaahu ‘alayhi wa sallam, said: "The whole earth has been made for us a place of worship and its soil has been made for us a means of purification." [Muslim]
Also, shoes are in principle pure even if the person walks on impure lands with them. This is because the earth that he treads on after that purifies them. It was narrated on the authority of Abu Hurayrah that the Prophet, sallallaahu ‘alayhi wa sallam, said: "If one of you treads on impurities with his shoes, the soil purifies them." [Abu Daawood] Thus, it is permissible for the Muslim to perform prayer while wearing shoes on condition that they are free from any impurities. The Prophet, sallallaahu ‘alayhi wa sallam, said: "Whoever comes to the Masjid (whose floor was then covered with pebbles) should look at his sandals; if he found impurities attached to them, let him remove the impurities and perform prayer in them." [Abu Daawood]
Therefore, people's treading on the ground or the seats with their shoes does not make them impure. If the ground and the seats do not have impurities, there will be no harm in sitting on the seats or if the clothes touch the ground. However, if you are sure that there is an impurity on the ground or the seats and that it touched your clothes or your body, you must wash the area of the body or the clothes which is touched by an impurity.