<p>I use a swim tether in hotel pools. There's a small one that goes around your ankles <a href="http://www.amazon.com/gp/redirect.html?ie=UTF8&linkCode=ur2&camp=1789&creative=9325&tag=kickrunners-20&location=http%3A%2F%2Fwww.amazon.com%2FPoolToy-The-Original-Swimcords%2Fdp%2FB0006N8TAE" rel="norewrite" target="_blank">http://www.amazon.com/PoolToy-The-Original-Swimcords/dp/B0006N8TAE</a>, you could make the same out of some nylon webbing, velcro and thin bungee. The swim cords one is much smaller to carry around than the stretch cordz one that goes around your waist. Its not exactly the same as swimmign and 20 mintues will likely exhuast you but its a great workout and will build some power. </p>